Question

Find all the real square roots of a. .0064 and b. -.0081

Answer 1

Answers:  0.08 and -0.08; 0.09i and -0.09i.

When taking square roots, we take the positive and negative answers.  This gives us the first answer.

For the second answer, we rewrite -0.0081 as a complex number:
$\sqrt{-0.0081}=\sqrt{0.0081i^2}=i\sqrt{0.0081}=\pm0.09i$