Question

初中数学 想先化简再求值

Answer 1

=[x²/(x-2)-4/(x-2)]×1/x(x+2)
=(x²-4)/(x-2)×1/x(x+2))
=(x+2)(x-2)/(x-2)×1/x(x+2)
=1/x
当x=√2-1时
原式=1/（√2-1）=√2+1

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谢谢你😊

Answer 2

原式=[x²/(x-2)-4/(x-2)]*1/x(x+2)
=(x²-4)/(x-2)*1/x(x+2)
=(x+2)(x-2)/(x-2)*1/x(x+2)
=(x+2)*1/x(x+2)
=1/x
=1/(√2-1)
=√2+1

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谢谢你😊

第一步怎么得出来的

追答

采纳就告诉你

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我知道了

Answer 3

=[x²/(x-2) + (-4)/(x-2)] ·1/(x²+2x)
=(x²-4)/(x-2) ·1/(x²+2x)
=(x+2)(x-2)/(x-2) ·1/(x²+2x)
=(x+2)/x(x+2)
=1/x

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谢谢你\!