a, Với x khác -3 ; 3 ; -7
\(P=\left(\dfrac{x^2+1-x\left(x-3\right)-5\left(x+3\right)}{x^2-9}\right):\left(\dfrac{2x+10-x-3}{x+3}\right)\)
\(=\left(\dfrac{1+3x-5x-15}{x^2-9}\right):\left(\dfrac{x+7}{x+3}\right)=\dfrac{-14-2x}{x^2-9}:\left(\dfrac{x+7}{x+3}\right)\)
\(=\dfrac{-2\left(x+7\right)\left(x+3\right)}{\left(x^2-9\right)\left(x+7\right)}=\dfrac{-2}{x-3}\)
b, Ta có \(\left[{}\begin{matrix}x-1=2\\x-1=-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\left(ktm\right)\\x=-1\end{matrix}\right.\)
Thay vào ta được -2/(-1-3) = 1/2
c, Ta có \(\dfrac{x+5}{6}=-\dfrac{2}{x-3}\Rightarrow x^2+2x-15=-12\Leftrightarrow x^2+2x-3=0\Leftrightarrow x=1\left(tm\right);x=-3\left(ktm\right)\)
