当x=-1 y=-2时求代数式[2x^2-(x+y)(x-y)][(-x-y)(-x+y)+2y^2]的值

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[2x^2-(x+y)(x-y)][(-x-y)(-x+y)+2y^2]
=[2x^2-x^2+y^2][x^2-y^2+2y^2]
=(x^2+y^2)^2
=(1+4)^2
=25