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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