Question

Which is a zero of the quadratic function f(x) = 4x2 + 24x + 11?

x = –9.25
x = –5.5
x = 0.5
x = 3.25

Answer 1

Use the quadratic formula: x = [−24 ± sqrt(24^2 − 4·4·11)]/(2·4) = [−24 ± sqrt(400)]/8 = [−24 ± 20]/8.
Thus x = (−24+20)/8 = −1/2 or x = (−24−20)/8 = −11/2 = −5.5.

Answer: x = −5.5.