Question

what is 7x sqaured =-21

Answer 1

$7x^2=-21$

we need to clear x

$\begin{gathered} x^2=\frac{-21}{7} \\ x^2=-3 \end{gathered}$

we can't have a square root of a negative number in real numbers, if we use complex numbers we can obtain the next values for x

$x=\pm i\sqrt[]{3}$