Use the quadratic formula to solve the equation.
-$$x ^ { 2 } + 14 x + 85 = 0$$
A) $\{ - 7 - 36 i , - 7 + 36 i \}$
B) $\{ - 7 - 6 i , - 7 + 6 i \}$
C) $\{ - 7 + 6 i \}$
D) $\{ - 13 , - 1 \}$

Question

Quizplus · Accepted Answer

The quadratic formula is $$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$. For the equation $x^2 + 14x + 85 = 0$, $a = 1$, $b = 14$, and $c = 85$. Plugging these into the formula gives $$x = \frac{-14 \pm \sqrt{14^2 - 4(1)(85)}}{2(1)} = \frac{-14 \pm \sqrt{196 - 340}}{2} = \frac{-14 \pm \sqrt{-144}}{2} = \frac{-14 \pm 12i}{2} = -7 \pm 6i$$, which matches choice B.

Use the Quadratic Formula to Solve the Equation x2+14x+85=0x ^ { 2 } + 14 x + 85 = 0x2+14x+85=0

Use the Quadratic Formula to Solve the Equation $x ^ { 2 } + 14 x + 85 = 0$