解：x^2+y^2=(x-y)^2+2xy=3^2-10=-1x^2y-xy-xy^2=xy(x-1-y)=-5×(3-1)=-10(x+y)^2=(x-y)^2+4xy=3^2+4×(-5)=-11
(x-y)^2 =x^2 -2xy +y^2 x^2 + y^2 = 19 (x+y)^2 = 29 X^2 -xy + xy^2= -3-（4*根号下29）
