x^2+y^2=2, xy=1, how to find x and y I have problems when doing these equations when I don't know any variable's value.
Can someone please explain how to do this and possibly give some tips when it comes to solving these problems?
Well, I know x = 1 and y = 1, but what about this one:
a-b=3, a:b=3:2, find a^2-b^2
(I am not quite is a:b=3:2 = a/b:3/2 or it was meant to be that way)

Since $x^2+y^2=2$ and $xy=1$, then$$(x-y)^2=x^2+y^2-2xy=2-2=0.$$Therefore, $x=y$. But now the second equation becomes $x^2=1$. So, the only solutions are $x=y=1$ and $x=y=-1$.
