ACT Math: Functions 2 — Questions and Answers
Question 1: If f(x) = 3x - 5, what is f(4)?
- 7 (Correct answer)
- 12
- 17
- -2
Correct answer: 7
f(4) = 3(4) - 5 = 12 - 5 = 7.
Question 2: If g(x) = x^2 + 2x, what is g(-3)?
- 3 (Correct answer)
- -3
- 15
- 9
Correct answer: 3
g(-3) = (-3)^2 + 2(-3) = 9 - 6 = 3.
Question 3: What is the domain of f(x) = 1/(x - 2)?
- All real numbers except 2 (Correct answer)
- All real numbers except 0
- x > 2
- All real numbers
Correct answer: All real numbers except 2
The denominator cannot be zero, so x cannot equal 2.
Question 4: If f(x) = 2x + 1 and g(x) = x - 3, what is f(g(5))?
- 5 (Correct answer)
- 11
- 13
- 7
Correct answer: 5
g(5) = 2, then f(2) = 2(2) + 1 = 5.
Question 5: Which value of x makes f(x) = x^2 - 9 equal to zero?
- 3 (Correct answer)
- 9
- 0
- 6
Correct answer: 3
x^2 - 9 = 0 gives x = 3 or x = -3, so 3 is a solution.
Question 6: What is the slope of the linear function f(x) = -4x + 7?
- -4 (Correct answer)
- 7
- 4
- -7
Correct answer: -4
In y = mx + b form, the coefficient of x is the slope, which is -4.
Question 7: If h(x) = x^2, what is h(x + 1)?
- x^2 + 2x + 1 (Correct answer)
- x^2 + 1
- x^2 + 2x
- 2x + 1
Correct answer: x^2 + 2x + 1
h(x + 1) = (x + 1)^2 = x^2 + 2x + 1.
ACT Math: Functions 2
If f(x) = 3x - 5, what is f(4)?