Question

quiz 3.2.1 - solving quadratics by fac
value: 4
solve for x.
$x^2 + 5x - 84$
a. 6, 1
b. -7, 12
c. 7, -12
d. -4, 8

Explanation:

Step1: Set quadratic equal to 0

$x^2 + 5x - 84 = 0$

Step2: Factor the quadratic

Find two numbers that multiply to $-84$ and add to $5$: $12$ and $-7$.
$(x + 12)(x - 7) = 0$

Step3: Solve for x

Set each factor to 0:
$x + 12 = 0 \implies x = -12$
$x - 7 = 0 \implies x = 7$

Answer:

c. 7, -12