Solve.
-$$x ^ { 2 } + x + 7 = 0$$
A) $- \frac { 1 } { 2 } \pm \frac { 3 \sqrt { 3 } } { 2 }$
B) $\frac { 1 } { 2 } \pm \frac { 3 \sqrt { 3 } } { 2 }$
C) $- \frac { 1 } { 2 } \pm \frac { 3 \sqrt { 3 } } { 2 } \mathrm { i }$
D) $\frac { 1 } { 2 } \pm \frac { 3 \sqrt { 3 } } { 2 } \mathrm { i }$

Question

Quizplus · Accepted Answer

This quadratic equation can be solved using the quadratic formula, $$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$, where $a = 1$, $b = 1$, and $c = 7$. Plugging these values into the formula gives $$x = \frac{-1 \pm \sqrt{1^2 - 4(1)(7)}}{2(1)} = \frac{-1 \pm \sqrt{1 - 28}}{2} = \frac{-1 \pm \sqrt{-27}}{2}$$. Since $\sqrt{-27} = 3\sqrt{3}i$, the solutions are $$x = -\frac{1}{2} \pm \frac{3\sqrt{3}}{2}i$$, which matches choice C.

Solve - x2+x+7=0x ^ { 2 } + x + 7 = 0x2+x+7=0

Solve
- $x ^ { 2 } + x + 7 = 0$