Đáp án+Giải thích các bước giải:
`(2x+1)/(x-1)=(5(x-1))/(x+1)` (đk: `x\ne+-1`)
`↔(2x+1)/(x-1)=(5x-5)/(x+1)`
`↔((2x+1)(x+1))/(x^2-1)=((5x-5)(x-1))/(x^2-1)`
`→(2x+1)(x+1)=(5x-5)(x-1)`
`↔2x^2+3x+1=5x^2-10x+5`
`↔5x^2-2x^2-10x-3x+5-1=0`
`↔3x^2-13x+4=0`
`↔(3x-1)(x-4)=0`
`↔` \(\left[ \begin{array}{l}3x-1=0\\x-4=0\end{array} \right.\) `↔` \(\left[ \begin{array}{l}x=\dfrac{1}{3}(tm)\\x=4(tm)\end{array} \right.\)
Vậy `S={1/3;4}`
