11)
`<=> (x-3)(x+3)+2(x-3)=0`
`<=> (x-3)(x+3+2)=0`
`<=> (x-3)(x+5)=0`
\(< =>\left[{}\begin{matrix}x-3=0\\x+5=0\end{matrix}\right.\\ < =>\left[{}\begin{matrix}x=3\\x=-5\end{matrix}\right.\)
12)
`<=> (x+3)(x-1+x+3)=0`
`<=> (x+3)(2x+2)=0`
\(< =>\left[{}\begin{matrix}x+3=0\\2x+2=0\end{matrix}\right.\\ < =>\left[{}\begin{matrix}x=-3\\x=-1\end{matrix}\right.\)
13)
`<=> (x-5)(x-5+3)=0`
`<=> (x-5)(x-2)=0`
\(< =>\left[{}\begin{matrix}x-5=0\\x-2=0\end{matrix}\right.\\ < =>\left[{}\begin{matrix}x=5\\x=2\end{matrix}\right.\)
14)
`<=> (2x+1)(2x+1+x-1)=0`
`<=> 3x(2x+1)=0`
\(< =>\left[{}\begin{matrix}3x=0\\2x+1=0\end{matrix}\right.\\ < =>\left[{}\begin{matrix}x=0\\x=-\dfrac{1}{2}\end{matrix}\right.\)
15)
`<=> (x+2)(x+1-x+3)=0`
`<=> (x+2)*4=0`
`<=> x+2=0`
`<=> x=-2`
