Question

求分式加减

一。x/3-（x+1）/3
二。(x+y)/3-(x-y)/2
三。(x+2)/x-(x^2-4)/3
四。(x+1)/1+(x-1)/1-(x^2-1)/(x^2+1)

Answer 1

一。x/3-（x+1）/3
二。(x+y)/3-(x-y)/2
三。(x+2)/x-(x^2-4)/3
四。(x+1)/1+(x-1)/1-(x^2-1)/(x^2+1)

你的所有分子分母搞错了
1、3/x-3/(x+1)
=[3(x+1)-3x]/x(x+1)
=3/x(x+1)

2、3/(x+y)-2/(x-y)
=[3(x-y)-2(x+y)]/(x+y)(x-y)
=(3x-3y-2x-2y)/(x+y)(x-y)
=(x-5y)/(x+y)(x-y)

3、x/(x+2)-3/(x+2)(x-2)
=[x(x-2)-3]/(x+2)(x-2)
=(x²-2x-3)/(x+2)(x-2)

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