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Big Ideas Math Integrated I, 2016

BI

Big Ideas Math Integrated I, 2016 View details

3. Function Notation

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Exercise 15 Page 125

Substitute 7 for m(x).

-2

Practice makes perfect

To find the value of x that will make the function equal to 7, we will substitute 7 for m(x) in the given function rule. Then, we can solve for x.

m(x)=4x+15

m(x)= 7

7=4x+15

▼

Solve for x

LHS-15=RHS-15

7- 15=4x+15- 15

Subtract terms

-8=4x

.LHS /4.=.RHS /4.

-8/4=4x/4

MoveNegNumToFrac

Put minus sign in front of fraction

-8/4=4x/4

Calculate quotient

-2=4x/4

MovePartNumRight

a* b/c=a/c* b

-2=4/4 * x

a/a=1

-2=1 * x

Identity Property of Multiplication

-2=x

Rearrange equation

x=-2

When x=-2, the function equals 7.

Checking Our Answer

Verifying Our Solution

We can verify our solution by substituting x=-2 into the function and evaluating.

m(x)=4x+15

x= -2

m( -2)=4( -2)+15

a(- b)=- a * b

m(-2)=-4 * 2+15

Multiply

m(-2)=-8+15

Add terms

m(-2)=7

When x=-2, m(x)=7, so our solution is correct.

Subchapter links

Communicate Your Answer p.121

Monitoring Progress p.122-124

Exercises p.125-126