Question

Factor to find the zeros of the function defined by the quadratic expression.

4x2 − 24x − 108
A) x = 3 or x = 9
B) x = 3 or x = −9
C) x = −3 or x = 9
D) x = −3 or x = −9

Answer 1

ANSWER

C) x = −3 or x = 9

EXPLANATION

The given quadratic function is:

$4 {x}^{2} - 24x - 108$

To find the zeros, we equate to zero.

$4 {x}^{2} - 24x - 108 = 0$

Divide through by 4

${x}^{2} - 6x - 27 = 0$

Factor to get,

${x}^{2} + 3x - 9x - 27 = 0$

$x(x + 3) - 9(x + 3) = 0$

$(x + 3)(x - 9) = 0$

Use the zero product property,

$x = - 3 \: or \: x = 9$