Graphing
Calculator
Math
Worksheets
Algebara
Solver
Chart
Maker
A+ A− B

How do you evaluate functions?

question
Answer
The same way that you substitute values into equations!
For instance, consider the following problem,
What is the value of $$ x $$ given the equation $$ y = 2x $$ when $$ x = 5 $$ ?
Substitute '5' in for x :
The one new aspect of function notation is the emphasis on input and output .
example of how to evaluate a function in math
Example 2
What is the value of $$ x $$ given the equation $$ y = x-5 $$ when $$ x = 7 $$ ?
Substitute '7' in for x :
Again, this new way involves an input and output
example 2 of how to evaluate a function
Function Machine
You can think of $$ f(x)$$ as a function machine.
The function machine, or $$ f(x)$$ , takes input inside . The machine processes this input and produces an output value
function machine-math functions evaluate
Practice Problems


Problem 1) Let $$ k(x) =3x $$.
Evaluate $$ k (5 ) $$
function machine question
Step 1


Problem 2) Let $$ g(x) =3x^2 + 7x $$.
Evaluate $$ g( 4) $$
function machine g of x input is 5
Step 1


Problem 3) Let $$ h(x) =\sqrt{x^3 -4}-|x| $$.
Evaluate $$ h( 5) $$
Step 1


Problem 4) Let $$ f(x) = -3x^2 + 5x - 1 $$.
Evaluate $$ f(6) $$
Step 1


Problem 5) The height in meters of a projectile at t seconds can be found by the function $$ h(t) = -5t^2 + 40t + 1.2 $$.
Find the height of the projectile 4 seconds after it is launched.
Step 1


Problem 6) A substance has a half life of 26 years. The amount of remaining substance in grams after t years can be found by the function $$ h(t) = 250 (0.5)^{ \frac{t}{25} } $$.
How much substance remains after 98 years?
Step 1