Question

If x²+ y²= 80 and xy = 12, find the value of (x - y)².​

Answer 1

$(x-y)^2\\\\=x^2+y^2 -2xy\\\\=80-2(12)\\\\=80-24\\\\=56$

Answer 2

We need to factorise (x−y) 2

We know the identity (a−b)2 =a2 −2ab+b2

Thus we have (x−y)2 =x2 −2xy+y2