What have you tried? These are ratios.

Can you take it from there?

Have you considered multiplication?#2.√2 (√32 - √2 )

Can you take it from there?

Have you considered squaring?#3.( 5√2)^2

Can you take it form there?

Have you considered prime factorization?#4 simplify √90

Let's see your work. Have you made any efforts? Do you want the volunteers, here, to do all your homework or take your exam? Give us a clue where you are and how we can help you.