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计算 (1)[(x+2)(x-2)]^2 (2)(x+2y-3)(x-2y+3)(3)(x+y)^2(x-y)^2-(x

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计算 (1)[(x+2)(x-2)]^2 (2)(x+2y-3)(x-2y+3)(3)(x+y)^2(x-y)^2-(x-y)(x+y)(x^2+y^2)
计算 (1)[(x+2)(x-2)]^2 (2)(x+2y-3)(x-2y+3)(3)(x+y)^2(x-y)^2-(x
计算 (1)[(x+2)(x-2)]^2 =[x^2-4]^2=x^4-8x^2+16
(2)(x+2y-3)(x-2y+3)=[x+(2y-3)][x-(2y-3)]=x^2-(2y-3)^2=x^2-4y^2+12y-9
(3)(x+y)^2(x-y)^2-(x-y)(x+y)(x^2+y^2)
=(x+y)(x-y)[(x+y)(x-y)-x^2-y^2]
=(x^2-y^2)*(-2y^2)
=2y^4-2x^2y^2