I have the first bit to this problem but I do not know how to prove that x^2 is even and then y is even. I am using the contradiction method. Here is what I have so far :

Assume sqrt2 is rational

therefore sqrt2=(x/y)^2

2y^2=x^2

thanks for any help.

p.s how do you write with apprioate symbols? I have never done maths on the computer.