Practice Math Questions for Praxis: Solving Functions

If you enjoy solving functions (and why wouldn't you?), then you'll have a great time on the Praxis Core exam. The following practice questions will help you put the fun into "function" by asking you to first solve a simple function, and then to find the value of two functions combined!

Practice questions

1. If f(x) = x – 2, what is the value of f(3)?

   A. 1 B. 4 C. 3 D. 0 E. 2

2. For the two following functions, what is the value of f(g(1))?

   f(x) = 8x² – 2x + 12

   g(x) = 3x + 5

   A. 508 B. 415 C. 29 D. 580 E. 18

Answers and explanations

1. The correct answer is Choice (A). Because f(3) replaces the x in f(x) with 3, put 3 in for x in x – 2:

   

2. The correct answer is Choice (A). First, find the value of g(1):

   

   Because g(1) is 8, f(g(1)) is f(8):

   

   Therefore, f(g(1)) is 508, Choice (A).