Question

If x+y=18 and xy=72 what is the value of x2+y2

Answer 1

Step-by-step explanation:

on squaring both sides

(x+y)^2=18^2

x^2+y^2+2xy=324

x^2+y^2+2×72=324

x^2+y^2+144=324

x^2+y^2=324-144

x^2+y^2=180