Practice Math Questions for Praxis: Solving Functions - dummies

By Carla Kirkland, Chan Cleveland

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).