初二数学的题

x-1分之1减x+1分之1减x^2+1分之2
=1/(x-1)-1/(1+x)-2/（x^2+1)
=[(1+x)-(x-1)]/(x^2-1) -2/(x^2+1)
=2/(x^2-1)-2/(x^2+1)
=[2(x^2+1)-2(x^2-1)/(x^2+1)(x^2-1)
=4/(x^2+1)(x^2-1)

x^4-1分之4

解：
x-1分之1减x+1分之1减x^2+1分之2
=x^2-1分之2减x^2+1分之2
=x^4-1分之4

1/(x-1)-1/(x+1)-2/(x2+1)
=(x+1)/(x2-1)-(x-1)/(x2-1)-2/(x2+1)
=2/(x2-1)-2/(x2+1)
=2(x2+1)/(x4-1)-2(x2-1)/(x4-1)
=4/(x4-1)
其中x2代表x的平方，x4代表x的四次方

都同分就可以了 结果是x^4-1分之4