SOLVING AN EQUATION

CHRISTIAN TEKEU

8-9-2011

GRADE 7

• Go over solving equation

• Know how to solve an algebraic equation

• Explain how to write an equation

• Check for the answer

PURPOSE

OBJECTIVE

• ASSIGN VALUES TO VARIABLE

• Collect information about variable

• Use the information to solve an equation.

• Variable + Number = Number or

• Number = Variable + Number

• X + 125 = 98• 98 =X +125

Standard equation

• Using the addition property. A=B

• If you add C• on both side the

equation remain the same

• A+C=B+C

HOW TO SOLVE AN EQUATION

EXAMPLE #1

• X+125=98 You want to find the variable X

• You add -125 on both sides of the equation

• X+125-125 =98-125 by solving you have:

• X=-27

• Or 98=125+X the same procedure but the variable is on the right.

• You will have -27=X

EXAMPLE #2

• X + 2 = 2/3

• Add -2 on both sides x+2-2=2/3-2

• x=2/3-2/1 then you have x=2/3-6/3

• x= -4/3

CHECK FOR THE ANSWER

.Use the original equation to check the answer.

. Check for the equation balance.

Example: X + 125 =98 for X=-27

Plot the value in the equation

you have -27+ 125= 98

98=98 the equation is balance

WRITING ALGEBRIC EQUATION

• Example #1 John has $17 in his piggy bank, how money does he need to buy a game that cost $87

• First name your variable before writing the equation.

• Let represent the game by the variable n

• n represents the amount of money needed

• The algebric equation is: 17+n =87

EXAMPLE #2

Sentence Algebraic equation

A number increased by nine is fifteen X + 9=15

Twice a number is eighteen 2X= 18

Four less than a number is 20 4-X=20

Rose is x years old. In thirteen years she will be twenty four years old

X+13=24

Closure

• Use addition property to solve an equation

• The variable is positive

• Write an algebraic equation

• Check your answer

Assignment

students work in group.

*4x-3x+10=58

*X+3=5-3/4

*Suzy made a withdrawal from her saving account, her old balance was $350,and her new balance is $ 280

*Thirty two is twice a number increase by 8

*Twice a number, decreased by 29 is 7