Question

Find value of x2+ y2, if x+y = 8 and xy= 2

Answer 1

I assume you want to find x^2+y^2 which is "x squared plus y squared"

x+y = 8
(x+y)^2 = 8^2 ... square both sides
x^2+2xy+y^2 = 64 ... use the FOIL rule
x^2+2(2)+y^2 = 64 ... replace xy with 2 (since xy = 2)
x^2+4+y^2 = 64
x^2+y^2+4 = 64
x^2+y^2+4-4 = 64-4 ... subtract 4 from both sides
x^2+y^2 = 60

Answer: 60