求x^2-2x/x^2-1除以(x-1-2x-1/x+1),先化简,再求值,x=1/2

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求x^2-2x/x^2-1除以(x-1-2x-1/x+1),先化简,再求值,x=1/2

求x^2-2x/x^2-1除以(x-1-2x-1/x+1),先化简,再求值,x=1/2
求x^2-2x/x^2-1除以(x-1-2x-1/x+1),先化简,再求值,x=1/2

求x^2-2x/x^2-1除以(x-1-2x-1/x+1),先化简,再求值,x=1/2
x^2-2x/x^2-1除以(x-1-2x-1/x+1),
=x^2-2x/x^2-1除以x^2-2x/x+1
=x(x-2)/(x+1)(x-1)*(x+1)/x(x-2)
=1/x-1
=1/(1/2-1)
=-2

^^^是什么意思?


原式={x(x-2)/[(x+1)(x-1)]}÷[(x-1)(x+1)/(x-1)-(2x-1)/(x+1)]
={x(x-2)/[(x+1)(x-1)]}÷[(x²-1-2x+1)/(x+1)]
={x(x-2)/[(x+1)(x-1)]}÷[(x²-2x)/(x+1)]
={x(x-2)/[(x+1)(x-1)]}×{(x+1)/[x(x-2)]}
=1/(x-1)
当x=1/2时
原式=1/(1/2-1)
=1/(-1/2)
=-2