已知x+y=2,xy=0,求x²;+y²;與(x-y)²;

已知x+y=2,xy=0,求x²;+y²;與(x-y)²;

x²;+y²;
=(x+y)²;-2xy
=2²;-0
=4
(x-y)²;
=(x+y)²;-4xy
=2²;-0
=4