Exercise 7 Page 269

Practice makes perfect

a We can substitute the x=-2 into the equation and solve for a.

ax-8=4-x

Substitute

x= -2

a( -2)-8=4-( -2)

Multiply

-2a-8=4-(-2)

SubNeg

a-(- b)=a+b

-2a-8=4+2

AddTerms

Add terms

-2a-8=6

AddEqn

LHS+8=RHS+8

-2a=14

DivEqn

.LHS /(-2).=.RHS /(-2).

a=-7

When a=-7, the solution is x=-2.

b We can substitute the x=12 into the equation and solve for a.

ax-8=4-x

Substitute

x= 12

a( 12)-8=4- 12

Multiply

12a-8=4-12

SubTerm

Subtract term

12a-8=-8

AddEqn

LHS+8=RHS+8

12a=0

DivEqn

.LHS /12.=.RHS /12.

a=0

When a= , the solution is x=12.

c We can substitute the x=3 into the equation and solve for a.

ax-8=4-x

Substitute

x= 3

a( 3)-8=4- 3

Multiply

3a-8=4-3

SubTerm

Subtract term

3a-8=1

AddEqn

LHS+8=RHS+8

3a=9

DivEqn

.LHS /3.=.RHS /3.

a=3

When a=3, the solution is x=3.

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Exercises p.268-269

Exercise 7 Page 269

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