Evaluating Functions
Evaluating a function means finding the value of f(x) =… or y =… that corresponds to a given value of x. To do this, simply replace all the x variables with whatever x has been assigned. For example, if we are asked to evaluate f(4), then x has been assigned the value of 4.
Example: Given that f(x) = 3x + 6, find f(2)
Solution: This means we will evaluate the function when x has been assigned the value of 2. The first step is to replace every x with 2. Then evaluate the function by following order of operations (BEDMAS).
f(x) = 3x + 6
So, we have :
f(2) = 3(2) + 6
= 6 + 6
= 12
Example: Given the function f(x) = 5x2 - 2√x + 7, evaluate f(-3).
Solution: Substitute -3 in for x and evaluate.
f(-3) = 5(-3)2 - 2√-3 +7
= 5(9) -2√4
= 45 – 4
= 41
Example 1:
Example 2:
