#### Answer

$c^2=\dfrac{E}{m}$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
To solve the given equation, $
E=mc^2
$ for $
c^2
,$ use the properties of equality to isolate the variable.
$\bf{\text{Solution Details:}}$
Using the properties of equality to isolate the variable, the equation above is equivalent to
\begin{array}{l}\require{cancel}
E=mc^2
\\\\
\dfrac{E}{m}=\dfrac{mc^2}{m}
\\\\
\dfrac{E}{m}=c^2
\\\\
c^2=\dfrac{E}{m}
.\end{array}