1/(x-1) -2/(x平方-1) 化简

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1/(x-1) -2/(x平方-1) 化简
1/(x-1) -2/(x平方-1) 化简

1/(x-1) -2/(x平方-1) 化简
1/(x-1) -2/(x平方-1)
=1/(x-1)-2/(x+1)(x-1)
=(x+1)/(x+1)(x-1)-2/(x+1)(x-1)
=(x-1)/(x+1)(x-1)
=1/(x+1)

1/(x-1) -2/(x^2-1)
=1/(x-1)-2/(x+1)(x-1) 因为x^2-1=(x+1)(x-1)
=(x+1)/(x+1)(x-1)-2/(x+1)(x-1)
=(x+1-2)/(x+1)(x-1)
=(x-1)/(x+1)(x-1)
=1/(x+1)

1/(x-1) -2/(x平方-1) =1/(x-1) -2/(x-1) (x+1)=1/(x-1)-[1/(x-1)-1/(x+1)]=1/(x+1)

x2-1=(x+1)(x-1),将前后两式合并得
原式=x+1-2/(x+1)(x-1)
=x-1/(x+1)(x-1)
=1/x+1