Use the quadratic formula to solve the equation.
-$x ^ { 2 } + 14 x + 74 = 0$
A) $- 7 - 25 i , - 7 + 25 i$
B) $- 7 - 5 i , - 7 + 5 i$
C) $- 2 , - 12$
D) $- 7 + 5 \mathrm { i }$

Question

Quizplus · Accepted Answer

The quadratic formula is $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$. For the equation $x^2 + 14x + 74 = 0$, $a = 1$, $b = 14$, and $c = 74$. Plugging these into the formula gives $x = \frac{-14 \pm \sqrt{14^2 - 4(1)(74)}}{2(1)} = \frac{-14 \pm \sqrt{196 - 296}}{2} = \frac{-14 \pm \sqrt{-100}}{2} = \frac{-14 \pm 10i}{2} = -7 \pm 5i$, which matches choice B.

Use the Quadratic Formula to Solve the Equation x2+14x+74=0x ^ { 2 } + 14 x + 74 = 0x2+14x+74=0

Use the Quadratic Formula to Solve the Equation $x ^ { 2 } + 14 x + 74 = 0$