Answer
$\color{blue}{\left\{-\dfrac{2\sqrt{21}}{3}, \dfrac{2\sqrt{21}}{3}\right\}}$
Work Step by Step
Add $6m^2$ to both sides to obtain:
\begin{align*}
-6m^2+56+6m^2&=0+6m^2\\\\
56&=6m^2\\\\
\frac{56}{6}&=m^2\\\\
\frac{28}{3}&=m^2\\\\
m^2&=\frac{28}{3}
\end{align*}
Take the square root of both sides to obtain:
\begin{align*}
\sqrt{m^2}&=\pm\sqrt{\frac{28}{3}}\\\\
m&=\pm\sqrt{\frac{4(7)}{3}}\\\\
m&=\pm\sqrt{\frac{4(7)\cdot 3}{3\cdot 3}}\\\\
m&=\pm\sqrt{\frac{4(21)}{3^2}}\\\\
m&=\pm \frac{2\sqrt{21}}{3}\\\\
\end{align*}
Therefore, the solution set is $\color{blue}{\left\{-\dfrac{2\sqrt{21}}{3}, \dfrac{2\sqrt{21}}{3}\right\}}$.
