ĐKXĐ:\(\left\{{}\begin{matrix}x\ne-3\\x\ne1\end{matrix}\right.\)
\(\dfrac{2x}{x+3}-\dfrac{x}{x-1}=\dfrac{-9x-3}{x^2+2x-3}\\ \Leftrightarrow\dfrac{2x\left(x-1\right)}{\left(x-1\right)\left(x+3\right)}-\dfrac{x\left(x+3\right)}{\left(x-1\right)\left(x+3\right)}=\dfrac{-\left(9x+3\right)}{\left(x-1\right)\left(x+3\right)}\\ \Leftrightarrow\dfrac{2x^2-2x}{\left(x-1\right)\left(x+3\right)}-\dfrac{x^2+3x}{\left(x-1\right)\left(x+3\right)}+\dfrac{9x+3}{\left(x-1\right)\left(x+3\right)}=0\\ \Leftrightarrow\dfrac{2x^2-2x-x^2-3x+9x+3}{\left(x-1\right)\left(x+3\right)}=0\\ \Rightarrow x^2+4x+3=0\\ \Leftrightarrow\left(x+1\right)\left(x+3\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-1\left(tm\right)\\x=-3\left(ktm\right)\end{matrix}\right.\)
đk : x khác -3 ; 1
\(2x^2-2x-x^2-3x=-9x-3\Leftrightarrow x^2+4x+3=0\)
\(\Leftrightarrow\left(x+1\right)\left(x+3\right)=0\Leftrightarrow x=-3\left(ktm\right);x=-1\left(tm\right)\)
