Question

Let xy=6 and x2 + y2 = 23 what is the value of (x+y)??

Answer 1

I'll assume that x2 = x^2 and y2 = y^2 and the answer is sqrt{35}.

Explanation:

This problem invovles completing the square, so if I square (x+y), I get

x^2+2xy+y^2, and since xy = 6, 2xy = 12, 23+12 = 35, and your answer is sqrt{35}.