Tip
Finding the value of a function that is defined by an algebraic equation involves substituting a value of x into the expression. For example, if we are given that x = 6 and an equation f(x) = 10 − 5(x − 3) then f(6) = 10 − 5(6 − 3) = 10 − 15 = −5.
Sample Problem
Let the function f be defined as f(x) = 2x + 7. For what value of a is f(a) equal to 11?
Answer Options
(A) 2
(B) 9
(C) 15
(D) 18
(E) 29
View Correct Answer
(A) 2
Since f(a) = 2a + 7 = 11, then 2a = 4, and a = 2.
