(2xy-y)(x+y)-4(x-2y)的二次方

(2xy-y)(x+y)-4(x-2y)的二次方 ,二次方是（x-2y）的,求最后化简结果

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（2xy-y)(x+y)-4(x-2y)²
=2x²y+2xy²-xy-y²-4(x²-4xy+4y²)
=2x²y+2xy²-xy-y²-4x²+16xy-16y²
=2x²y-4x²+2xy²+15xy-17y²