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问题: [x^(-1)+x+x^0][x^(-1/2]-x^(1/2)]

[x^(-1)+x+x^0][x^(-1/2]-x^(1/2)]=[x^(-1/2)]^3-[x^(1/2)]^3=x^(-3/2)-x^3/2.
中间省略的几步是怎样的。请详细的写出来,谢谢。

解答:

就是运用公式:a^3-b^3=(a-b)(a^2+ab+b^2)

[x^(-1)+x+x^0][x^(-1/2]-x^(1/2)]
=[(x^-1/2)^2+x^1/2*x^(-1/2)+(x^1/2)^2][x^(-1/2)-x^1/2]
=[x^(-1/2)]^3-[x^(1/2)]^3
=x^(-3/2)-x^3/2.