Question

5x + 15 - 2x(3 + x)=0

Answer 1

\(\Leftrightarrow5\left(x+3\right)-2x\left(x+3\right)=0\\ \Leftrightarrow\left(5-2x\right)\left(x+3\right)=0\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=-3\end{matrix}\right.\)

Answer 2

\(\Leftrightarrow\left(x+3\right)\left(5-2x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=\dfrac{5}{2}\end{matrix}\right.\)