Question

 

Answer 1

`(3x)/(x+1)-3=x/(x+1)` (đkxđ: `x≠-1)`

`<=>(3x)/(x+1)`\(-\dfrac{3\left(x+1\right)}{x+1}=\dfrac{x}{x+1}\)

\(⇔ 3 x − 3 ( x + 1 ) = x\)

\(⇔ 3 x − 3 x − 3 = x\)

\(⇔ x = − 3 (nhận)\)

Answer 2

=>3x-3(x+1)=x

=>x=3x-3x-3

=>x=-3(nhận)

Answer 3

\(\dfrac{3x}{x+1}-3=\dfrac{x}{x+1}\)

\(ĐK:x\ne-1\)

\(\Leftrightarrow\dfrac{3x}{x+1}-\dfrac{x}{x+1}=3\)

\(\Leftrightarrow\dfrac{2x}{x+1}=3\)

\(\Leftrightarrow\dfrac{2x}{x+1}-3=0\)

\(\Leftrightarrow\dfrac{2x-3x-3}{x+1}=0\)

\(\Leftrightarrow-x-3=0\)

\(\Leftrightarrow x=-3\)

Vậy \(S=\left\{-3\right\}\)

 

Answer 4