Q. For what values of p is the function

f(x,y) = { (x+y)^p/(x^2 +y^2) where (x,y) can not equal (0,0)

0 else

continuous on R^2

I'm finding this problem very confusing. Please help. I know that 0 <= (x-y)^2 =

x^2 -2*x*y+y^2 so 2*x*y <= x^2 +y^2

and I have to use the inequality

(x+y)^2 = x^2 +2*x*y +y^2 <= 2*x^2 +2*y^2

How do I proceed from here. Thanks in advance.