Question

已知x+y=1,xy=16分之3计算(1)(x-y)^2(2)x^3y-2x^2y^2+xy^3

Answer 1

(x-y)^2

=(x+y)²-4xy

=1-4x3/16

=1-3/4

=1/4

x^3y-2x^2y^2+xy^3

=xy(x²-2xy+y²)

=xy(x-y)²

=3/16x1/4

=3/64