Question

If x^2 + y^2 = 90, xy = 15 Find the value of (x-y)^2​

Answer 1

The value of (x-y)^2​ is 60

Given: x^2 + y^2 = 90, xy = 15

Solution: (x-y)^2+4xy= x^2 + y^2 -2xy+4xy

= x^2 + y^2 +2xy

(x-y)^2 = 90 +2×(15) -4(15)

=90 + 30 - 60

=60