2.0 Graphs of Functions 2

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    CHAPTER 2GRAPHS OF FUNCTIONS II

    2.1 GRAPHS OF FUNCTIONS

    The graph of a function is a set of points on

    the Cartesian Plane that satisfy the function

    Information is presented in the form of graphs

    Graph are widely used in science and technology

    Graphs are very useful to researchers, scientists

    and economist

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    The different type of functions and respective power of x

    Type of

    function

    General form Example Highest

    power of variable x

    Linear

    Quadratic

    Cubic

    Reciprocal

    y = ax + c

    y = ax2 + bx + c

    y = ax3 + bx2 + cx + d

    y = a

    x

    y = 3x

    y = -4x + 5

    y = 2x2

    y = -3x2 + 2xy = 2x2 + 5x + 1

    y = 2x3

    y = -3x3 + 5x

    y = 2x

    3

    - 3x + 6

    y = 4

    x

    y = - 2

    x

    1

    3

    -1

    2

    y = ax3

    y = ax3 + bxy = ax3 + bx + c

    a 0

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    LINEAR FUNCTION

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    LINEAR FUNCTION

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    QUADRATIC FUNCTION

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    QUADRATIC FUNCTION

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    QUBIC FUNCTION

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    QUBIC FUNCTION

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    RECIPROCAL FUNCTION

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    RECIPROCAL FUNCTION

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    Using calculator to complete the tables

    Using the scale given to mark the pointson the x-axis and y-axis

    Plotting all the points using the scale given

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    COMP

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    CALC MemoryCALC MemoryExample 1Example 1Calculate the resultforY = 3X 5,

    when X = 4, and when X = 6

    )3X

    -5

    CALC

    3X 5

    4 = 7CALC 6 = 13

    ALPHA

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    CALC MemoryCALC MemoryExample 2Example 2Calculate the resultforY = X2 + 3X 12,when X = 7, and when X = 8

    ) 3X

    x2 +ALPHA

    )X

    - 21CALC X2 + 3X 12

    7 = 58CALC

    8 = 76

    ALPHA

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    CALC MemoryCALC MemoryExample 3Example 3Calculate the resultforY = 2X2 + X 6,when X = 3, and when X = -3

    )

    3

    X

    x2 +ALPHA

    )X

    - 6CALC 2X2

    + X 63 = 15

    CALC (-) =9

    ALPHA

    2

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    CALC MemoryCALC MemoryExample 4Example 4Calculate the resultforY = -X3 + 2X + 5,when X = 2, and when X = -1

    )

    1

    X

    x2

    + 2

    ALPHA

    )

    X

    + 5-X3 + 2X + 5 2 = 1CALC

    (-) = 4

    ALPHA

    (-)SHIFT x3

    CALC

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    Example 5Example 5Calculate the resultforY = 6 when X = -3,

    X

    and when X = 0.5

    )XALPHA

    3CALC (-) = -2

    6

    CALC 0 . 125 =

    ab/c 6x

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    Example 6Example 6Calculate the resultforY = 6 when X = -3,

    X

    and when X = 0.5

    )XALPHA

    3CALC (-) = -2

    6

    CALC 0 . 125 =

    x-1 6x-1

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    Y = -2X2 + 40

    X 0 0.5 1 1.5 2 3 3.5 4

    Y

    Y = X3 3X + 3

    X -3 -2 -1 0 0.5 1 1.5 2Y

    Y = -16XX -4 -3 -2 -1 1 2 3 4

    Y

    40 39.5 38 35.5 32 22 15.5 8

    -15 1 5 3 16.25 1.875 51

    4 5.33 8 16 -16 -8 -5.33 -4

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    2(4)2 + 5(4) 1 = 51Using Calculator

    2 ( )4 x2 + 5 ( 4 )

    - 1 =

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    (-2)3 - 12(-2) + 10 = 26

    Using Calculator

    2( ) x2

    + 1 0

    (-) 1

    =

    SHIFT - 2

    2( )(-)

    2( ) 3

    + 1 0

    (-) 1

    =

    V- 2

    2( )(-)

    OR

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    Using Calculator6

    (-3)= -2

    3( )6 (-) =

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    x -5 -4 -3 -2 -1 0 1 2 3

    y 15 8 0 -1 0 3 15

    y = x2 + 2x

    y = (

    -3

    ) 2 + 2 (

    -3

    ) = 3

    y = (

    2

    )2

    + 2 (

    2

    ) = 8

    3

    8

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    x -4 -2.5 -1 -0.5 0.5 1 2 3.2 4

    y 1 1.6 8 -8 -4 -1.25 -1

    4

    2

    y = -4( )

    =

    y = -4( )

    =

    -1

    4 -2-2

    y = -4

    x

    Completing the table of values

    -1 2

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    2.4 3.0 3.9

    x-axis scale : 2 cm to 2 units

    Marking the points on the x-axis and y-axis

    2 4

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    -4 -2

    -3.6 -3.0 -2.1

    x-axis scale : 2 cm to 2 units

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    10

    15

    12

    14.5

    13.5

    y-axis scale : 2 cm to 5 units

    10.75

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    -20

    -15

    -18

    -15.5

    -16.5

    y-axis scale : 2 cm to 5 units

    -19.25

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    The x-coordinate and y-coordinate

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    xA

    B

    x

    x

    x

    C

    D

    (-3,2)

    (2,0)

    (4,-3)

    (0,-4)

    Ex

    (4,4)

    F

    x

    (-7,-2)

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    -5

    -1 1

    x

    x

    xx

    A

    B

    C

    D

    Ex (-0.5,2)

    (-1,-3)

    (0,3)

    (0.3,1.5)

    (0.5,-1.5)

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    -2

    -1 1

    x x

    xx

    A

    B

    CD (-1,-1.2)

    (0,1.2)

    (0.3,0.6)

    (0.2,-1)

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    -10

    -1 1

    x

    x

    xx

    A

    B

    C

    D(-1,-6)

    (0,5)

    (0.3,3)

    (0.5,-3)

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    2.1 A Drawing the Graphs

    Construct a table for a chosen range of x values, for example-4 x 4

    Draw the x-axis and the y-axis and suitable scale for each axis

    starting from the origin

    Plot the x and y values as coordinate pairs on the Cartesian Plane

    Join the points to form a straight line (using ruler) or smooth curve

    (using French Curve/flexible ruler) with a sharp pencil

    Label the graphs

    To draw the graph of a function, follow these steps;

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    2.1 A Drawing the Graphs

    Draw the graph of y = 3x + 2for -2 x 2

    solution

    x

    y

    -2 0

    -4 2 8

    0-2-4 2 4

    -2

    -4

    2

    4

    6

    8

    x

    y

    GRAPH OF A LINEAR FUNCTION

    8

    3 + 2

    22

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    Draw the graph of y = x2 + 2x for -5 x 3

    solution

    x -5 -4 -3 -2 -1 0 1 2 3

    y 15 8 0 -1 0 3 15

    y = x2 + 2x

    3 83

    + 22

    -3 -3

    y

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    x

    x

    x

    x

    x

    x

    x

    x

    x

    y

    x0 1 2

    2

    4

    6

    8

    10

    -1-3-4-5

    16

    14

    12

    -2 3

    y = x2 + 2x

    GRAPH OF A QUADRATIC FUNCTION

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    Draw the graph of y = x3 - 12x + 3 for -4 x 4

    solution

    x -4 -3 -2 -1 0 1 2 3 4

    y -13 12 19 14 3 -8 -13 -6 19

    y = x3 - 12x + 3

    -13

    - 123

    -4 -4 + 3

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    0 1 2 3 4-1-2-3-4

    -5

    -10

    -15

    5

    10

    15

    20

    25

    y

    x

    x

    x

    x

    x

    x

    x

    x

    xx

    GRAPH OF A CUBIC FUNCTION

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    Draw the graph of y = -4 for -4 x 4.

    x

    solution

    y = -4

    x

    x -4 -2.5 -1 -0.5 0.5 1 2 3.2 4

    y 1 1.6 4 8 -8 -4 -2 -1.25 -14

    -4

    -1

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    1 2 3 4-1-2-3-4 0

    y

    x

    2

    4

    6

    8

    -2

    -4

    -6

    -8

    X

    X

    X

    X

    X

    X

    X

    X

    X

    GRAPH OF A RECIPROCAL FUNCTION

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    xx

    USING FRENCH CURVE

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    x

    x

    x

    x

    USING FRENCH CURVE

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    x

    x

    x

    USING FRENCH CURVE

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    -10

    -15

    -20

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    x

    x

    x

    x

    x

    x

    x

    x

    x

    y

    x0 1 2

    2

    4

    6

    8

    10

    -1-3-4-5

    16

    14

    12

    -2 3-3.5

    5

    y = 11

    -4.4 2.5

    2.1 B Finding Values of Variable from a Graph

    y = x2 + 2x

    Find

    (a)the value of

    y whenx = -3.5

    (b) the value of

    x when

    y = 11

    solution

    From the graph;

    (a)y = 5

    (b) X = -4.4, 2.5

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    x

    x

    x

    x

    x

    x

    x

    x

    x

    y

    x0 1 2

    2

    4

    6

    8

    10

    -1-3-4-5

    16

    14

    12

    -2 3-3.5

    5

    2.1 B Finding Values of Variable from a Graph

    y = x2 + 2x

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    x

    x

    x

    x

    x

    x

    x

    x

    x

    y

    x0 1 2

    2

    4

    6

    8

    10

    -1-3-4-5

    16

    14

    12

    -2 3

    5

    11

    2.1 B Finding Values of Variable from a Graph

    y = x2 + 2x-4.4 2.5

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    x =1.5

    y

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    x

    y

    0 1 2 3 4

    8

    6

    4

    2

    -2

    -4

    -6

    -8

    -4 -3 -2 -1

    xx

    x

    x

    x

    x

    x

    x

    -2.2

    -1.2 1.8

    3.4

    ( a ) y = -2.2

    ( b ) x = -1.2

    Find

    (a)the value of

    y when

    x = 1.8

    (b) the value of

    x when

    y = 3.4

    solution

    y = -4

    x

    Values obtained fromthe graphs are

    approximations

    Notes

    Id tif i th h f G h f

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    2.1 C Identifying the shape of a Graph from

    a Given Function

    LINEAR a

    y

    x

    y = x

    0

    b

    x

    y = -x + 2

    0

    2

    y

    Id tif i g th h f G h f

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    2.1 C Identifying the shape of a Graph from

    a Given Function

    QUADRATIC a

    y

    x

    y = x2

    0

    bx

    y = -x2

    0

    y

    Id tif i g th h f G h f

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    2.1 C Identifying the shape of a Graph from

    a Given Function

    CUBIC a

    y

    x

    y = x3

    0

    b

    x

    y = -x3 + 2

    0

    2

    y

    Id tif i g th h f G h f

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    2.1 C Identifying the shape of a Graph from

    a Given Function

    RECIPROCAL a

    y

    x0

    b

    x0

    y

    y = 1x

    y = -1

    x

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    2.1 D Sketching Graphs ofFunction

    Sketching a graph means drawing a graph withoutthe actual data

    When we sketch the graph, we do not use

    a graph paper, however we must know the important

    characteristics of the graph such as its general form

    (shape), the y-intercept and x-intercept

    It helps us to visualise the relationship of the variables

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    EXAMPLE y = 2x + 4

    4

    -2 0

    y

    x

    find the x-intercept ofy = 2x + 4.

    Substitute y = 0

    2x + 4 = 0

    2x = -4

    x = -2Thus, x-intercept = -2

    find the y-intercept of

    y = 2x + 4.

    Substitute x = 0

    y = 2(0) + 4y = 4

    Thus, y-intercept = 4

    draw a straight line that

    passes x-intercept and y-intercept

    y = 2x + 4

    A Sketching The Graph of A Linear Function

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    B Sketching The Graph of A Quadratic Function

    EXAMPLE y = -2x2 + 8

    a < 0

    the shape of the graph is

    y-intercept is 8

    find the x-intercept of

    y = -2x2 + 8.

    Substitute y = 0-2x2 + 8 = 0

    -2x2 = -8

    x2 = 4Thus, x-intercept = -2 and 2

    x0

    y

    -2 2

    8

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    B Sketching The Graph of A Cubic Function

    EXAMPLE y = -3x3 + 5

    a < 0

    the shape of the graph is

    y-intercept is 5

    x0

    y

    5

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    2.2 The Solution of An Equation By Graphical

    Method

    Solve the equation x2 = x + 2

    Solution

    x2

    = x + 2

    x2 - x 2 = 0

    (x 2)(x + 1) = 0

    x = 2, x = -1

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    2

    y

    1

    3

    4

    0-1 1-2 2 x

    y = x2

    y = x + 2

    A

    B

    Let y = x + 2

    and y = x2

    Draw both

    graphs on

    the same

    axes

    Look at thepoints of

    intersection:

    A and B.

    Read the

    values of the

    coordinates

    of x.

    x = -1 and

    x = 2

    Solve the equation x2 = x + 2 by using the Graphical Method

    The Solution of An Equation By Graphical

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    2.2 The Solution of An Equation By Graphical

    Method

    12.(a) Complete Table 1 for the equation y = x2 +2x by writing down the values of y

    when x = -3 and 2.

    x -5 -4 -3 -2 -1 0 1 2 3

    y 15 8 0 -1 0 3 15

    (b) By using scale of 2 cm to 1 unit on the x-axis and 2 cm to 2 units on the y-axis,

    draw the graph of y = x2 +2x for-5 x 3.

    (c) From your graph, find(i) the value of y when x = -3.5,

    (ii) the value of x when y = 11.

    (d) Draw a suitable straight line on your graph to find a value of x which satisfies

    the equation of x 2 + x 4 = 0 for-5 x 3.

    TABLE 1

    2 2 The Solution of An Equation By Graphical

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    2.2 The Solution of An Equation By Graphical

    Method

    The graph y = x2 - 5x - 3 is drawn. Determine the suitable straight line

    to be drawn to solve each of the following equations.

    a) x2 - 5x - 3 = 4

    b) x2 - 5x - 3 = 2x + 4

    c) x2 - 5x - 2 = x + 4

    d) x2 - 5x - 10 = 0

    e) x2

    - 7x - 2 = 0

    EXAMPLE 1

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    solution

    a) x2 - 5x - 3 = 4 x2 - 5x - 3 = y4

    Therefore, y = 4 is the suitable straight line

    b) x2 - 5x - 3 = 2x + 2 x2 - 5x - 3 = y2x + 2 y

    Therefore, y = 2x + 2 is the suitable straight line

    The graph y = x2 - 5x - 3 is drawn. Determine the suitable straight line

    to be drawn to solve the equation: x2 - 5x - 3 = 4

    y

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    solution

    c) x2 - 5x - 2 = x + 4

    - 1

    -1 on both sides

    Therefore, y = x + 3 is the suitable straight line

    x2 - 5x - 2 = x + 4 - 1

    x2 - 5x - 3 = x + 3x + 3

    The graph y = x2 - 5x - 3 is drawn. Determine the suitable straight line

    to be drawn to solve the equation: x2 - 5x 2 = x + 4

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    solution

    d) x2 - 5x - 10 = 0 Rearrange the equation

    Therefore, y = 7 is the suitable straight line

    x2 - 5x = 10

    x2 - 5x = 10 - 3- 3

    x2 - 5x - 3 = 77

    -3 on both sides

    The graph y = x2 - 5x - 3 is drawn. Determine the suitable straight line

    to be drawn to solve the equation: x2 - 5x - 10 = 0

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    solution

    e) x2 - 7x - 2 = 0 Rearrange the equation

    Therefore, y = 2x - 1 is the suitable straight line

    x2 = 7x + 2

    x2 = 7x + 2 - 5x - 3- 5x - 3

    x2 - 5x - 3 = 2x -12x -1

    -5x - 3 on both sides

    The graph y = x2 - 5x - 3 is drawn. Determine the suitable straight line

    to be drawn to solve the equation: x2 - 7x - 2 = 0

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    Alternative Method

    Since a straight line is needed, we used to eliminate the term, x2.

    The following method can be used

    y = x2 - 5x - 3 1

    0 = x2 - 7x - 2 2

    1 - 2 y-0 = -5x - (-7x) - 3 - ( -2)

    y = 2x - 1

    e

    The graph y = x2 - 5x - 3 is drawn. Determine the suitable straight line

    to be drawn to solve the equation: x2 - 7x - 2 = 0

    2 2 The Solution of An Equation By Graphical

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    2.2 The Solution of An Equation By Graphical

    Method

    The graph y = 8 is drawn. Determine the suitable straight line

    x

    to be drawn to solve each of the following equations.

    a) 4 = x + 1

    x

    b) -8 = -2x - 2x

    EXAMPLE 2

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    solution

    4 = x + 1xMultiply both sides by 2a

    We get 8 = 2x + 2

    x

    Therefore, y = 2x + 2 is the suitable straight line

    2x + 2

    The graph y = 8 is drawn. Determine the suitable straight line

    x

    to be drawn to solve each the equation: 4 = x + 1

    x

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    solution

    -8 = -2x - 2

    x

    Multiply both sides by -1

    b

    We get 8 = 2x + 2

    x

    Therefore, y = 2x + 2 is the suitable straight line

    2x + 2

    The graph y = 8 is drawn. Determine the suitable straight line

    x

    to be drawn to solve each the equation: - 8 = -2x - 2

    x

    2 2 The Solution of An Equation By Graphical

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    2.2 The Solution of An Equation By Graphical

    Method

    12.(a) Complete Table 1 for the equation y = x2 +2x by writing down the values of y

    when x = -3 and 2.

    x -5 -4 -3 -2 -1 0 1 2 3

    y 15 8 0 -1 0 3 15

    (b) By using scale of 2 cm to 1 unit on the x-axis and 2 cm to 2 units on the y-axis,

    draw the graph of y = x2 +2x for-5 x 3.

    (c) From your graph, find

    (i) the value of y when x = -3.5,

    (ii) the value of x when y = 11.

    (d) Draw a suitable straight line on your graph to find a value of x which satisfies

    the equation of x 2 + x 4 = 0 for-5 x 3.

    TABLE 1

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    12. (a)

    x -5 -4 -3 -2 -1 0 1 2 3

    y 15 8 0 -1 0 3 15

    y = x2 + 2x

    y = (-3 ) 2 + 2 (-3) = 3

    y = ( 2 )2 + 2 ( 2 ) = 8

    8

    solution

    3

    12. (a) y

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    12. (a)

    x

    x

    x

    xx

    x

    x

    x

    x

    x0 1 2

    2

    4

    6

    8

    10

    -1-3-4-5

    16

    14

    12

    -2 3

    12. (c)

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    ( )

    x

    x

    x

    xx

    x

    x

    x

    x

    y

    x0 1 2

    2

    4

    6

    8

    10

    -1-3-4-5

    16

    14

    12

    -2 3-3.5

    5

    y = 11

    -4.4 2.5

    Answer:

    (i) y = 5.0

    (ii) x = -4.4

    x = 2.5

    12. (d)

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    ( )

    x

    x

    x

    xx

    x

    x

    x

    x

    y

    x0 1 2

    2

    4

    6

    8

    10

    -1-3-4-5

    16

    14

    12

    -2 3

    y = x2+2x + 00 = x2+ x - 4-

    y = x +4

    x 0 -4

    y 4 0

    x

    x1.5-2.5

    Answer:

    (d) x = 1.5

    x = -2.5

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    a 2 + b + c 0

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    ax2 + bx + c = 0

    x2+ x 4 = 0

    a = 1 b = 1 c = -4

    MODE EQN

    1 1Unknowns ?

    2 3Degree?

    2 3

    2 a ? 1 = b ? 1 = c ?

    (-) 4 x1 = 1.561552813 = x2 = -2.561552813

    Press 3x

    =

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    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

    2.3 A Determining Whether a Given Point Satisfies y = ax + b,

    y > ax + b or y < ax + b

    How can we determine whether a given point satisfiesy = 3x + 1, y < 3x + 1or y > 3x + 1 ?

    2 3 REGION REPRESENTING INEQUALITIES IN TWO VARIABLES

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    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

    2.3 A Determining Whether a Given Point Satisfies y = ax + b,

    y > ax + b or y < ax + b

    Let us consider the point (3,5). The point can only satisfies one of the

    following relations:

    (a) y = 3x + 1 (b) y < 3x + 1 (c) y > 3x + 1

    y 3x + 1

    5 3(3) + 1

    5 10

    =

    3x - 1.

    (a) (1,-1) (b) (3,10) (c) (2,9)

    EXAMPLE

    2 3 REGION REPRESENTING INEQUALITIES IN TWO VARIABLES

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    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

    2.3 A Determining Whether a Given Point Satisfies y = ax + b,

    y > ax + b or y < ax + b

    For point (1,-1)

    When x = 1, y = 3(1) - 1 = 2

    Since the y-coordinate of the point (1,-1) is -1, which is less than 2,

    we conclude that y < 3x - 1 . Therefore, the point (1,-1) satisfies the relationy < 3x - 1

    solution a

    REGION REPRESENTING INEQUALITIES IN TWO VARIABLES

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    2.3REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

    2.3 A Determining Whether a Given Point Satisfies y = ax + b,

    y > ax + b or y < ax + b

    For point (3,10)

    When x = 3, y = 3(3) - 1 = 8

    Since the y-coordinate of the point (3,10) is 10, which is greater than 8,

    we conclude that y > 3x - 1 . Therefore, the point (3,10) satisfies the relationy > 3x - 1

    solution b

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    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

    2.3 A

    For point (-1,-4)

    When x = -1, y = 3(-1) - 1 = -4

    Since the y-coordinate of the point (-1,-4) is -4, which is equal to -4,

    we conclude that y = 3x - 1 . Therefore, the point (-1,-4) satisfies the relationy = 3x - 1

    solution c

    Determining Whether a Given Point Satisfies y = ax + b,

    y > ax + b or y < ax + b

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    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

    2.3 BDetermining The Position of A Given Point Relative to

    y = ax + b

    All the points satisfying y < ax + b are below the graph

    All the points satisfying y = ax + b are on the graph

    All the points satisfying y > ax + b are above the graph

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    Q

    2.3 BDetermining The Position of A Given Point Relative to

    y = ax + b

    -2-4

    2

    4

    6

    8

    x

    y

    20

    -2

    -4

    4-6

    -8

    6

    P(4,8)

    Q(4,2)

    y < xy > x

    The point P(4,8) liesabove the line y = x.

    This region is represented

    by y > x

    The point Q(4,2) liesbelow the line y = x.

    This region is represented

    by y < x

    Q(4,4)

    The point Q(4,4) lies

    on the line y = x.This region is represented

    by y = x

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 BDetermining The Position of A Given Point Relative to

    y = ax + b

    -2-4

    2

    4

    6

    8

    x

    y

    20

    -2

    -4

    4-8

    -8

    8

    P(-8,6)

    Q(4,4)

    y < 3x + 2y > 3x + 2

    The point P(-8,6) lies

    above the line y = 3x + 2.

    This region is representedby y > 3x + 2

    The point Q(4,4) lies

    below the line y = 3x + 2.

    This region is represented

    by y < 3x + 2

    Q(2,8)

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 C Identifying The Region Satisfying y > ax + b or y < ax + b

    -2-4

    2

    4

    6

    8

    x

    y

    20

    -2

    -4

    4-8

    -8

    8

    Determine whether the

    shaded region in the graph

    satisfies y < 3x + 2 ory > 3x + 2

    EXAMPLE

    solution

    The shaded region is

    below the graph, y = 3x + 2.

    Hence, this shaded region

    satisfies y< 3x + 2

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 D Shading The Regions Representing Given Inequalities

    Symbol Type ofLine

    < or > Dashed

    Line

    or Solid line

    The type of line to be drawn depends

    on inequality symbol

    The table above shows thesymbols of inequality and thecorresponding type of line

    to be drawn

    HoT TiPsThe dashed line indicates that all points

    are not included in the region. The solid

    line indicates that all points on the line

    are included

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 D Shading The Regions Representing Given Inequalities

    0

    x

    y

    b

    0x

    y

    b

    0x

    y

    b

    0x

    y

    b

    y > ax + b

    a > 0y < ax + b

    a > 0

    y ax + b

    a > 0y ax + b

    a > 0

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 D Shading The Regions Representing Given Inequalities

    0x

    y

    by >ax + b

    a < 0

    0x

    y

    b y ax + b

    a < 0

    x

    y

    x

    y

    y ax + b

    a < 0b

    0

    y < ax + b

    a < 0

    0

    b

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 D Shading The Regions Representing Given Inequalities

    0

    y

    a

    x >a

    a > 0

    x

    y

    a

    x > a

    a < 0

    x

    y

    x

    y

    x a

    a < 0x a

    a > 0

    0a

    x0

    0 a

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 EDetermine The Region which Satisfies Two or More

    Simultaneous Linear Inequalities

    y

    x

    2

    0 2 3-3

    1

    EXAMPLEShade the region that satisfies

    3y < 2x + 6, 2y -x + 2 and x 3.

    X = 3

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    y

    x

    2

    0 2 3-3

    1

    X = 3

    Shade the region that satisfies

    3y < 2x + 6, 2y -x + 2 and x 3.

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    y

    x

    2

    0 2 3-3

    1

    X = 3A

    Region A satisfies 2y -x + 2, 3y < 2x + 6, and x 3

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 E Determine The Region which Satisfies Two or More

    Simultaneous Linear Inequalities

    y

    x

    2

    0 2 3-3

    1

    X = 3A

    Region A satisfies2y -x + 2,

    3y < 2x + 6, and x 3

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 E Determine The Region which Satisfies Two or More

    Simultaneous Linear Inequalities

    y

    x

    2

    0 2 3-3

    1

    X = 3A

    Region A satisfies

    2y > -x + 2,3y 2x + 6, and x < 3

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 E Determine The Region which Satisfies Two or More

    Simultaneous Linear Inequalities

    y

    x

    3

    0

    x = 3

    Region B satisfies

    y -x + 3,

    y < x , and x 3

    B

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 E Determine The Region which Satisfies Two or More

    Simultaneous Linear Inequalities

    y

    x

    3

    0

    x = 3

    Region B satisfies

    y > -x + 3,

    y x , and x < 3

    B

    2.3 REGIONREPRESENTING INEQUALITIESIN TWO VARIABLES

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    2.3 E Determine The Region which Satisfies Two or More

    Simultaneous Linear Inequalities

    y

    x

    3

    0

    x = -3Region C satisfies

    y > -x + 3,

    y -2x , and x >-3

    -3

    C

    y

    Region A satisfies

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    x

    x

    x

    xx

    x

    x

    x0 1 2

    2

    4

    6

    8

    10

    -1-3-4-5

    16

    14

    12

    -2 3x

    1.5-2.5

    y = x2 + 2x

    y = x + 4

    x

    x

    x

    Region A satisfies

    y x2 + 2x,

    y x + 4,

    and x 0

    A

    y

    Region A satisfies

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    x

    x

    x

    xx

    x

    x

    x0 1 2

    2

    4

    6

    8

    10

    -1-3-4-5

    16

    14

    12

    -2 3x

    1.5-2.5

    y = x2 + 2x

    y = x + 4

    x

    x

    x

    Region A satisfies

    y x2 + 2x,

    y x < 4,

    and x 0

    A

    ySPM Clone

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    Shade the region that satisfies

    y 2x +8, y x, and y < 8

    x0

    y = 8

    y = x

    y = 2x +8

    y 2x + 8

    y x

    y < 8

    ySPM Clone

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    Shade the region that satisfies

    y 2x +8, y x, and y < 8

    x0

    y = 8

    y = x

    K1

    y = 2x +8 3

    SPM Clone

    P2

    3y

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    3.

    x0

    y = 8

    y = x

    K2

    y = 2x +82

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    y

    xO

    y = 2x6

    y = 6

    Solution:

    x = 3

    K3

    x-intercept = -(-6 2) = 3

    x < 3, y 2x 6 and y -6

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    On the graphs provided, shade the region which satisfies

    the three inequalities y x - 4, y -3x + 12 and y > -4[3 marks]

    y

    x

    y = 3x+12

    O

    y = x4

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    y

    x

    y = 3x+12

    O

    y = x4

    y = 4

    Solution:

    K3

    y-intercept =-4

    y x - 4, y -3x + 12 and y > -4

    SPM 2003 PAPER 2

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    SPM 2003 PAPER 2

    REFER TO QUESTIONNO. 12

    12 ( a )

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    12.( a )

    x -4 -2.5 -1 -0.5 0.5 1 2 3.2 4

    y 1 1.6 8 -8 -4 -1.25 -1

    4

    2

    K1K1

    y = -4

    ( )

    =

    y = -4

    ( )

    =

    -1

    4 -2-2

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    12. ( a )

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    12.( a )

    x -4 -2.5 -1 -0.5 0.5 1 2 3.2 4

    y 1 1.6 8 -8 -4 -1.25 -14 2 K1K0

    y

    8X 12(b)

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    1 2 3 4-1-2-3-4 0 x

    2

    4

    6

    8

    -2

    -4

    -6

    -8

    X

    X

    XX

    X

    X

    X

    X

    X

    K1

    K1N1

    K1 N0

    ( )

    y

    8x12.( c )

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    x0 1 2 3 4

    6

    4

    2

    -2

    -4

    -6

    -8

    -4 -3 -2 -1

    xx

    x

    x

    x

    x

    x

    -2.2

    -1.2

    1.8

    3.4

    ( i ) y = -2.2

    ( ii ) x = -1.2

    P1

    P1

    y

    8x

    4 = 2x +3

    x

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    12.(d)

    x0 1 2 3 4

    6

    4

    2

    -2

    -4

    -6

    -8

    -4 -3 -2 -1

    xx

    x

    x

    x

    x

    x

    y = -2x - 3

    -2.4

    0.8

    K1K1

    x = - 2.4

    x = 0.8

    N1

    x

    - 4 = -2x - 3

    x

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