Evaluate Functions, Composition Intro

​Evalute Functions
(Intro to Composition)

By Jacquelyn Tarter

Multiple Choice

Let x = -3 given the function g(x) = 2x + 14.

What would g(-3) = ?

• 8

• -20

• 20

• -8

Fill in the Blanks

Let's say that we have the function, f(x) = 5x - 9. If we are told that the value of x = 7, what would be the value of f(7)?

Open Ended

What did you notice?

Q1: Evaluate f(x) = 5x - 9 when x = 7

Q2: Find f(g(x)) when f(x) = 5x - 9 and g(x) = 7

Composition of Functions

​What does that mean?!

Let's say that we are given 2 functions and sometimes a value for x. We have to be careful about our order of things we are given.

Drag and Drop

We have two functions.

f(x) = 5x - 9 and g(x) = 7

We need to find the f(g(x)).



Drag the correct input into the function.

f(​

Placeholder

)

Drag these tiles and drop them in the correct blank above

5x-9

7

26

Practice Problems

Multiple Choice

• f(-2) = -1

• f(-2) = -9

• f(-2) = 9

• f(-2) = 0

Fill in the Blanks

Find f(g(x)) given f(x)=2x+5, what is the value of g(x) = 4?

Multiple Choice

Evaluate f(g(x)) when f(x)=3x+1 and g(x) = 2

• 7

• 9

• 11

• 13

Multiple Choice

Evaluate f(g(x)) given f(x)=-2x+13 and g(x) = 10

• -7
• 1
• -8
• 7

Multiple Choice

Find f(g(x)) given f(x)=4x+5 and g(x) = 4

• 21
• -11
• -31
• 25

Multiple Choice

g(x) = 5 - 6x
Find g(-5)

• g(-5) = -25
• g(-5) = 6
• g(-5) = 4
• g(-5) = 35

Multiple Choice

Evaluate f(x) = x² for f(-8)

• 64
• -64
• -16
• 16

Multiple Choice

EVALUATE THE FUNCTION

• A

• B

• C

• D

Multiple Choice

Given $$f\left(x\right)=3x+9$$  , find $$f\left(-4\right)$$  .

• $$-3$$  

• $$21$$  

• $$8$$  

• $$-12$$  

Fill in the Blanks

What is the value of f(10)?

Hint: When x is 10, what is y?

Multiple Choice

Find f(g(x)) when f(x)=-x+3 and g(x) = 7

• -4
• -6
• 3
• 13

Multiple Choice

g(x) = 5 - 6x
Find g(-5)

• g(-5) = -25
• g(-5) = 6
• g(-5) = 4
• g(-5) = 35