c)\(\dfrac{x+3}{x-3}+\dfrac{36}{9-x^2}=\dfrac{x-3}{x+3}\)
\(\Leftrightarrow\dfrac{x+3}{x-3}-\dfrac{36}{x^2-9}=\dfrac{x-3}{x+3}\)
\(ĐKXĐ:\left[{}\begin{matrix}x-3\ne0\\x+3\ne0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x\ne3\\x\ne-3\end{matrix}\right.\)
\(\dfrac{x+3}{x-3}-\dfrac{36}{x^2-9}=\dfrac{x-3}{x+3}\)
\(\Leftrightarrow\dfrac{\left(x+3\right)\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}-\dfrac{36}{\left(x+3\right)\left(x-3\right)}=\dfrac{\left(x-3\right)\left(x-3\right)}{\left(x+3\right)\left(x-3\right)}\)
\(\Rightarrow x^2+3x+3x+9-36=x^2-3x-3x+9\)
\(\Leftrightarrow x^2-x^2+3x+3x-3x-3x=9-9-36\)
\(\Leftrightarrow0=-36\left(vôlí\right)\)
Vập phương trình vô ngiệm S={∅}
