The sum of two integers

Question

what is the sum of x+y when x^2+y^2=39^2?

Answer 1

Well one possibility is x=0 and y = 39, in which case the sum is 39.

Likewise x=39 and y=0 is another possibility...

y^2 = 39^2 - x^2

y = sqrt( 39^2 - x^2)

So when you choose a value for x, you can find the y using that formula above in bold.