Question

Giải pt: \(\dfrac{12}{x-1}-\dfrac{8}{x+1}=1\)

Answer 1

`ĐKXĐ: x ne +- 1`

`12/(x-1) - 8/(x+1) =1`

`<=> (12(x+1))/((x-1)(x+1)) - (8(x-1))/((x-1)(x+1)) = ((x-1)(x+1))/((x-1)(x+1))`

`<=>(12x+12-8x+8) = (x^2 -1)/((x-1)(x+1))`

`=>4x+20=x^2 -1`

`<=>x^2 -4x-21=0`

\(\Leftrightarrow\left[{}\begin{matrix}x=7\left(tm\right)\\x=-3\left(tm\right)\end{matrix}\right.\)