Function Notation

Function Notation

A concise way of substituting specific values for x

Written: f(x)

Read: "f of x"

Think of a function like a machine ...

• Substitute "in" value for x (or other variable)

• Calculate "out" value using Order of Operations

• Try this f(3) = 2x - 1

Multiple Choice

f(x) = x² + 7
x(2) = ______

• 10
• 11
• 13
• 12

Multiple Choice

g(x) = 3x + 1
g(2) = _______

• 6
• 7
• 8
• 9

Multiple Choice

Evaluate f(-2) if f(x) = x + 3

• -1
• 1
• 5
• -5

Determining "in" and "out" from a graph

• A graph is a set of ordered pairs (x, y)

• x is always the "input"

• f(x) - also called y - is always the "output"

• So, we can identify x & y in a graph and determine the function values!

Multiple Choice

What is x if
f(x) = -2?

• 4
• 0
• 3
• 8

Multiple Choice

For the function f(x) = -3(x-1) find f(0).

• 0
• -3
• 3
• -1

Multiple Choice

What is f(1)?

• 1
• 5
• 0
• 4

If you know what f(x) equals, you can solve for x

• If f(x) = 3x+1 and f(x) = 10 solve for x by setting 3x+1 = 10

• Subtract 1

• Divide by 3

• x (the input) is 3

Multiple Choice

If f(x) = -3x - 8, find f(-1).

• f(-1) = 5

• f(-1) = -5

• f(-1) = -12

• f(-1) = -10

Multiple Choice

If a question asks you to find f(2), what does that mean?

• Let x = 2

• Let y = 2

Multiple Choice

How do you read f(x)?

• f x

• f of x

• f parenthesis x

• f with an x inside parenthesis

Multiple Choice

Given f(x) = -4x - 10 and f(x) = 10. Find x

• x = -5
• x = 5
• x = -50
• x = 30