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Section 2-2 Linearity and Symmetry

Algebra 2 Section 2-2

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Page 1: Algebra 2 Section 2-2

Section 2-2Linearity and Symmetry

Page 2: Algebra 2 Section 2-2

Essential Questions

• How do you identify linear and nonlinear functions by examining equations or graphs?

• How do you determine whether graphs of functions have line or point symmetry?

Page 3: Algebra 2 Section 2-2

Vocabulary1. Linear Equation:

2. Linear Function:

3. Nonlinear Function:

4. Line Symmetry:

Page 4: Algebra 2 Section 2-2

Vocabulary1. Linear Equation: An equation that represents a

line where the highest power of a variable is 1

2. Linear Function:

3. Nonlinear Function:

4. Line Symmetry:

Page 5: Algebra 2 Section 2-2

Vocabulary1. Linear Equation: An equation that represents a

line where the highest power of a variable is 1

2. Linear Function: When a linear equation is written in function notation

3. Nonlinear Function:

4. Line Symmetry:

Page 6: Algebra 2 Section 2-2

Vocabulary1. Linear Equation: An equation that represents a

line where the highest power of a variable is 1

2. Linear Function: When a linear equation is written in function notation

3. Nonlinear Function: A function that is not linear; will have a power other than 1

4. Line Symmetry:

Page 7: Algebra 2 Section 2-2

Vocabulary1. Linear Equation: An equation that represents a

line where the highest power of a variable is 1

2. Linear Function: When a linear equation is written in function notation

3. Nonlinear Function: A function that is not linear; will have a power other than 1

4. Line Symmetry: When a graph can be folded on top of itself

Page 8: Algebra 2 Section 2-2

Vocabulary5. Line of Symmetry:

6. Point Symmetry:

7. Point of Symmetry:

Page 9: Algebra 2 Section 2-2

Vocabulary5. Line of Symmetry: The line that that divides a

graph into halves that fold over on top of itself

6. Point Symmetry:

7. Point of Symmetry:

Page 10: Algebra 2 Section 2-2

Vocabulary5. Line of Symmetry: The line that that divides a

graph into halves that fold over on top of itself

6. Point Symmetry: When a graph can be rotated 180º about a point so it ends on top of itself

7. Point of Symmetry:

Page 11: Algebra 2 Section 2-2

Vocabulary5. Line of Symmetry: The line that that divides a

graph into halves that fold over on top of itself

6. Point Symmetry: When a graph can be rotated 180º about a point so it ends on top of itself

7. Point of Symmetry: The point that is the center of a rotation

Page 12: Algebra 2 Section 2-2

Example 1State whether each function is a linear function. Write

yes or no. Explain.

a. g(x ) = 2x − 5 b. p(x ) = x3 + 2

c. 3y − 21x = 12

Page 13: Algebra 2 Section 2-2

Example 1State whether each function is a linear function. Write

yes or no. Explain.

a. g(x ) = 2x − 5 b. p(x ) = x3 + 2

c. 3y − 21x = 12

Yes; highest exponent on x is 1

Page 14: Algebra 2 Section 2-2

Example 1State whether each function is a linear function. Write

yes or no. Explain.

a. g(x ) = 2x − 5 b. p(x ) = x3 + 2

c. 3y − 21x = 12

Yes; highest exponent on x is 1

No; highest exponent on x is 3

Page 15: Algebra 2 Section 2-2

Example 1State whether each function is a linear function. Write

yes or no. Explain.

a. g(x ) = 2x − 5 b. p(x ) = x3 + 2

c. 3y − 21x = 12

Yes; highest exponent on x is 1

No; highest exponent on x is 3

Yes; highest exponent on x is 1

Page 16: Algebra 2 Section 2-2

Example 1State whether each function is a linear function. Write

yes or no. Explain.

a. g(x ) = 2x − 5 b. p(x ) = x3 + 2

c. 3y − 21x = 12

Yes; highest exponent on x is 1

No; highest exponent on x is 3

Yes; highest exponent on x is 1y = 7x + 4

Page 17: Algebra 2 Section 2-2

Example 2Matt Mitarnowski and Maggie Brann work part-time at a smoothie store. The number of hours they worked increased for the first 5 weeks on

the job. The graph models Matt’s weekly earnings, and the table models Maggie’s weekly

earning for these five weeks. State whether each relation is a linear function. Explain.

Page 18: Algebra 2 Section 2-2

Example 2Matt’s

Earnings

Earn

ings

($)

0306090

120150180210

Week0 1 2 3 4 5

Maggie’s EarningsWeek 1 2 3 4 5

Earnings ($)

60 120 180 210 240

Page 19: Algebra 2 Section 2-2

Example 2Matt’s

Earnings

Earn

ings

($)

0306090

120150180210

Week0 1 2 3 4 5

Maggie’s EarningsWeek 1 2 3 4 5

Earnings ($)

60 120 180 210 240

Matt’s earnings are linear as a line can be drawn through the points. Maggie’s

earnings are nonlinear as the values change by different amounts

Page 20: Algebra 2 Section 2-2

Example 3State whether the graph of the function has line symmetry. If so, identify the line of symmetry.

Page 21: Algebra 2 Section 2-2

Example 3State whether the graph of the function has line symmetry. If so, identify the line of symmetry.

This graph has line symmetry. It can reflect over the vertical line through x = 1.

Page 22: Algebra 2 Section 2-2

Example 4State whether the graph of the function has

point symmetry. If so, identify the point or points of symmetry.

Page 23: Algebra 2 Section 2-2

Example 4State whether the graph of the function has

point symmetry. If so, identify the point or points of symmetry.

This graph has point symmetry. It can rotate around the point (0,3).