Question

Which of the following is equivalent to the expression below?O A SiOB. -5,5O C. -2,5O D. 225

Answer 1

SOLUTION

We want to solve

$\sqrt[]{-20}$

This becomes

$\begin{gathered} \sqrt[]{-20} \\ \sqrt[]{-4\times5} \\ \sqrt[]{-1\times4\times5} \\ i\times\sqrt[]{4\times5} \end{gathered}$

The square root of a negative number is a complex number, so the square root of -1 is i

The answer becomes

$\begin{gathered} i\times\sqrt[]{4\times5} \\ i\times2\sqrt[]{5} \\ 2i\sqrt[]{5} \end{gathered}$