\(\Leftrightarrow\left(x-2\right)\left(x+2\right)+\left(x-9\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x+2+x-9\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=0\\2x-7=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{7}{2}\end{matrix}\right.\)
\(\Leftrightarrow\left(x-2\right)\left(x+2\right)+\left(x-9\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x+2+x-9\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(2x-7\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{7}{2}\end{matrix}\right.\)
