已知x-y=4,xy=21,求下列格式的值:(1)x^2y-xy^2(2)x^2+y^2
1个回答
(1)
x^2y-xy^2
=xy(x-y)
=21*4
=84
(2)
x^2+y^2
=(x-y)^2+2xy
=16+2*21
=58
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