If x - y = sqrt(3) and x + y = 2, then xy = ?
x - y = sqrt (3)
x + y = 2
Square both sides of these
x^2 - 2xy + y^2 = 3
x^2 +2xy + y^2 = 4 subtract the first equation from the second and we have that
4xy = 1 divide both sides by 4
xy = 1/4
