Đáp án:
`B=(x+1)/(x-1)`
Giải thích các bước giải:
ĐKXĐ : `x ne 1;-3`
`B=(5x-5)/(x^2+2x-3)+(2x+1)/(x+3)+(x-3)/(1-x)`
`=(5x-5)/((x-1)(x+3)) +(2x+1)/(x+3)-(x-3)/(x-1)`
`=(5x-5+(2x+1)(x-1)-(x-3)(x+3))/((x-1)(x+3))`
`=(5x-5+2x^2-x-1-x^2+9)/((x-1)(x+3))`
`=(x^2+4x+3)/((x-1)(x+3))=((x+1)(x+3))/((x-1)(x+3))`
`=(x+1)/(x-1)`
