How to Evaluate a Function, Function Input and Output

Two examples of function notation are the following:

f(x) = 2x
h(x) = x²

To evaluate a function, we substitute a given x value, a number in the domain, and see what number we get, which is a number in a range. Some examples:
The two functions below refer to functions listed up above.

To evaluate f(4) f(4) = 2(4) = 8 We just evaluated f(x) for the value x = 4.
evaluate h(-2) (-2)² = 4

Practice Problems

Practice Evaluating Functions

f(x) = 5x + 2
Evaluate f(2)

Answer

h(x) = 3x³ Evaluate h(2)

Answer

k(x) = 3x – 1 Evaluate k(-1)

Answer

s(x) = 2x² – 2x Evaluate s(3)

Answer

B(x) = x² – x³ Evaluate B(5)

Answer

Evaluating Functions in math

How Input Becomes Output

Practice Evaluating Functions