TeX source:

\begin{aligned} h(p)=3 & \\ p^{2}+2 p=3 & \text { Substitute the original function } h(p)=p^{2}+2 p \\ p^{2}+2 p-3=0 & \text { Subtract } 3 \text { from each side. } \\(p+3)(p-1)=0 & \text { Factor. } \end{aligned}