1/x-3 + x-9/x^2-9 -1/x – 1/x+1 giúp e vơia

2 bình luận về “1/x-3 + x-9/x^2-9 -1/x – 1/x+1 giúp e vơia”

1. $\text{$\dfrac{1}{x-3}$+ $\dfrac{x-9}{x^2 – 9}$}$

   $\text{=$\dfrac{1.(x+3)}{(x-3)(x+3)}$+ $\dfrac{x-9}{(x-3)(x+3)}$}$

   $\text{=$\dfrac{ x+3+ x – 9}{(x-3)(x+3)}$}$

   $\text{=$\dfrac{ 2x – 6}{(x-3)(x+3)}$}$

   $\text{=$\dfrac{ 2(x – 3)}{(x-3)(x+3)}$}$

   $\text{=$\dfrac{ 2}{x+3}$}$

   $\text{$\dfrac{-1}{x}$- $\dfrac{1}{x+1}$}$

   $\text{=$\dfrac{-1(x+1)}{x(x+1)}$- $\dfrac{1x}{x(x+1)}$}$

   $\text{=$\dfrac{-x-1-x)}{x(x+1)}$}$

   $\text{=$\dfrac{-2x-1)}{x(x+1)}$}$

   Trả lời
2. 1/(x-3)+(x-9)/(x^2-9)(ĐK:x\ne3; x\ne-3)

   =1/(x-3)+(x-9)/((x-3).(x+3))

   =(x+3+x-9)/((x-3).(x+3))

   =(2x-6)/((x-3).(x+3))

   =(2.(x-3))/((x-3).(x+3))

   =2/(x+3)

   $\\$

   -1/x-1/(x+1)(ĐK:x\ne0; x\ne-1)

   =(-(x+1)-x)/(x.(x+1))

   =(-x-1-x)/(x.(x+1))

   =(-2x-1)/(x.(x+1))

    

   Trả lời