ACT Math · Quadratic functions and equations
The function f(x) = 2(x+3)² - 8 has a minimum value of what?
The function has a minimum value of what?
Answer and explanation
Answer: F: -8
The function is in vertex form, , with , , and . Since , the parabola opens upward, so its minimum value is the -coordinate of the vertex, , choice F. The squared term is never negative, so the smallest it can be is , giving . Choice G () has the wrong sign. Choice H () is the -coordinate of the vertex, where the minimum occurs, not the minimum value. Choice J () uses the wrong sign for that -coordinate and also confuses it with the minimum value.
More Quadratic functions and equations questions
- Question 9What are the solutions to 2x² - 7x - 15 = 0?
- Question 52What are all real solutions to x^4 - 13x² + 36 = 0?
- Question 92An object is launched upward with the height function h(t) = -16t² + 64t + 5, where h is in feet…
- Question 104A ball is thrown so that its height is modeled by h(t) = -16t² + 40t, where h is in feet and t is…
- Question 106A parabola has the form f(x) = a(x-2)² - 5 and passes through the point (0, 3). What is f(4)?
- Question 133What are the solutions to x² + 6x - 7 = 0?
Learn the method behind questions like this one
The ACT Math course teaches each tested skill through lessons, step-by-step solutions to sample problems, the complete study guide and full-length practice tests.