Zero Factor Theorem
Since this is a multiplication that results in zero, we can separate its two terms and set them equal to zero to solve
[tex]\begin{gathered} a\mleft(a+14\mright)=0 \\ a=0\quad \mathrm{or}\quad \: a+14=0 \end{gathered}[/tex]We solve a+14=0
[tex]\begin{gathered} a+14=0 \\ a+14-14=0-14 \\ a=-14 \end{gathered}[/tex]Therefore, the solutions to the second degree equation are:
[tex]a=0,a=-14[/tex]