Question

How do I solve this?

Answer 1

Start with

`4i√(5)`

Since square root and square are two opposite operations, we have

`4i = √((4i)^2) = √(-16)`

So, we have

`4i√(5) = √(-16)\cdot√(5)`

Use the rule
`√(a)\cdot√(b)=√(ab)` to conclude

`√(-16)\cdot√(5) = √(-16\cdot 5) = √(-80)`