\(\dfrac{x-1}{x+5}=\dfrac{x-2}{x+3}\)
\(\Leftrightarrow\left(x-1\right)\left(x+3\right)=\left(x+5\right)\left(x-2\right)\)
\(\Leftrightarrow x^2+3x-x-3=x^2-2x+5x-10\)
\(\Leftrightarrow x^2+2x-3=x^2+3x-10\)
\(\Leftrightarrow x^2+2x-3-x^2-3x+10=0\)
\(\Leftrightarrow-x+7=0\)
\(\Leftrightarrow-x=-7\)
\(\Leftrightarrow x=7\)
Từ:\(\dfrac{x+1}{x+5}=\dfrac{x-2}{x+3}\Rightarrow\left(x-1\right)\left(x+3\right)=\left(x+5\right)\left(x-2\right)\)
\(\Rightarrow x\left(x+3\right)-x-3=x\left(x+5\right)-2\left(x+5\right)\)
\(\Rightarrow x^2+3x-x-3=x^2+5x-2x-10\)
\(\Rightarrow\) \(-3=-x-10\) \(\Rightarrow\) \(-x=-10+\left(-3\right)\) = \(-13\)
\(\Rightarrow x=13\) 
