Question

Evaluate:
(i) $\sqrt{-25}\times \sqrt{-49}$
(ii) $\sqrt{-36}\times \sqrt{16}$

Answer 1

We have

(i) $\sqrt{-25}\times \sqrt{-49}=\left(5i\right)\times \left(7i\right)=(35\times i^2)=35\times (-1)=-35$.

(ii) $\sqrt{-36}\times \sqrt{16}=\left(6i\right)\times 4=24i$