先化简,再求值(x-2y)(x方+2xy+4y方)-x(x-y)(x+y)+(2y)的三次方,x=5,y=-2

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先化简,再求值(x-2y)(x方+2xy+4y方)-x(x-y)(x+y)+(2y)的三次方,x=5,y=-2
先化简,再求值(x-2y)(x方+2xy+4y方)-x(x-y)(x+y)+(2y)的三次方,x=5,y=-2

先化简,再求值(x-2y)(x方+2xy+4y方)-x(x-y)(x+y)+(2y)的三次方,x=5,y=-2
(x-2y)(x方+2xy+4y方)-x(x-y)(x+y)+(2y)的三次方
=x³-(2y)³-x(x²-y²)+(2y)³
=x³-x³+xy²
=xy²
=5×(-2)²
=5×4
=20