Exercise 16 Page 125

To find the value of x that will make the function equal to 18, we will substitute 18 for k(x) in the given function rule. Then, we can solve for x.

k(x)=6x-12

Substitute

k(x)= 18

18=6x-12

▼

Solve for x

AddEqn

LHS+12=RHS+12

18+ 12=6x-12+ 12

AddTerms

Add terms

30=6x

DivEqn

.LHS /6.=.RHS /6.

30/6=6x/6

CalcQuot

Calculate quotient

5=6x/6

MovePartNumRight

a* b/c=a/c* b

5=6/6 * x

QuotOne

a/a=1

5=1 * x

IdPropMult

Identity Property of Multiplication

5=x

RearrangeEqn

Rearrange equation

x=5

When x=5, the function equals 18.

Checking Our Answer

Verifying Our Solution

We can verify our solution by substituting x=5 into the function and evaluating.

k(x)=6x-12

Substitute

x= 5

k( 5)=6( 5)-12

Multiply

Multiply

k(5)=30-12

SubTerm

Subtract term

k(5)=18

When x=5, k(x)=18, so our solution is correct.