Calculate: m^2=42

Expression: ${m}^{2}=42$

Take the square root of both sides of the equation and remember to use both positive and negative roots

$m=\sqrt{ 42 }$

Write the solutions, one with a $+$ sign and one with a $-$ sign

$\begin{array} { l }m=-\sqrt{ 42 },\\m=\sqrt{ 42 }\end{array}$

The equation has $2$ solutions

$\begin{align*}&\begin{array} { l }m_1=-\sqrt{ 42 },& m_2=\sqrt{ 42 }\end{array} \\&\begin{array} { l }m_1\approx-6.48074,& m_2\approx6.48074\end{array}\end{align*}$