Why isn’t square root of 8 - square root of 3 the same as (8-3)squared

Question

Must give the correct way of doing it and why it is wrong 

Answer 1

It is because of √8-√3≠(8-3)²

If you'd like to know why √8-√3 is not equal to √(8-3), then in some way you have to show it. For example, square √8-√3 and √(8-3)

(√8-√3)²=8-2√8√3-3=5-2√25=5-4√6

but

(√(8-3)²=8-3=5, which is not equal to 5-4√6, hence √8-√3≠√(8-3).