Tìm `x` $\dfrac{2}{x + 1  }$`-`$\dfrac{3}{x - 2}$`= 5/2 `

1 câu trả lời

`2/(x+1) - 3/(x-2) = 5/2`

`⇔ (2.(x-2))/((x+1)(x-2)) - (3.(x+1))/((x+1)(x-2)) = 5/2`

`⇔ ( 2x - 4 )/((x+1)(x-2)) - (3x + 3)/((x+1)(x-2)) = 5/2`

`⇔ ( 2x - 4 - 3x - 3 )/((x+1)(x-2)) = 5/2`

`⇔ (-x-1)/((x+1)(x-2)) = 5/2`

`⇔ (-(x+1))/((x+1)(x-2)) = 5/2`

`⇔ (-1)/(x-2) = 5/2`

`⇔ (-1.2)/(2(x-2)) = (5.(x-2))/(2(x-2))`

`⇔ (-2)/(2(x-2)) = (5x-10)/(2(x-2))`

`⇔ -2 = 5x - 10`

`⇔ -5x = -10 + 2`

`⇔ -5x = -8`

`⇔    x  = 8/5`

Vậy `x = 8/5`