a/ ĐKXĐ: \(x\ne2;3\)
\(\dfrac{x+3}{x-2}+\dfrac{5}{\left(x-2\right)\left(x-3\right)}=0\)
\(\Leftrightarrow\dfrac{\left(x+3\right)\left(x-3\right)+5}{\left(x-2\right)\left(x-3\right)}=0\)
\(\Leftrightarrow x^2-9+5=0\Leftrightarrow x^2=4\Rightarrow\left[{}\begin{matrix}x=-2\\x=2\left(l\right)\end{matrix}\right.\)
b/ ĐKXĐ: \(x\ne\pm\dfrac{3}{4}\)
\(\dfrac{12x^2+30x-21}{\left(4x-3\right)\left(4x+3\right)}+\dfrac{3x-7}{4x-3}-\dfrac{6x+5}{4x+3}=0\)
\(\Leftrightarrow12x^2+30x-21+\left(3x-7\right)\left(4x+3\right)-\left(6x+5\right)\left(4x-3\right)=0\)
\(\Leftrightarrow9x-27=0\Rightarrow x=3\)
c/ ĐKXĐ: \(x\ne-1;2\)
\(\dfrac{x+3}{\left(x+1\right)\left(x-2\right)}-\dfrac{4}{x+1}+\dfrac{2}{x-2}=0\)
\(\Leftrightarrow x+3-4\left(x-2\right)+2\left(x+1\right)=0\)
\(\Leftrightarrow-x+13=0\)
\(\Rightarrow x=13\)
