Solve by the most appropriate method.
-$3 m ^ { 2 } + 12 m + 5 = 0$
A) $m = \frac { - 12 \pm \sqrt { 21 } } { 3 }$
B)m $m = \frac { - 6 \pm \sqrt { 51 } } { 3 }$
C) $m = \frac { - 6 \pm \sqrt { 21 } } { 6 }$
D) $m = \frac { - 6 \pm \sqrt { 21 } } { 3 }$

Question

Quizplus · Accepted Answer

The quadratic formula $m = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$ is used. For $3m^2 + 12m + 5 = 0$, $a = 3$, $b = 12$, $c = 5$. The discriminant $b^2 - 4ac = 144 - 60 = 84$, so the roots are $m = \frac{-12 \pm \sqrt{84}}{6}$, which simplifies to $m = \frac{-6 \pm \sqrt{21}}{3}$.

Solve by the Most Appropriate Method 3m2+12m+5=03 m ^ { 2 } + 12 m + 5 = 03m2+12m+5=0

Solve by the Most Appropriate Method $3 m ^ { 2 } + 12 m + 5 = 0$