We have [tex]h(p)=p^2+2p[/tex] and [tex]h(p)=3[/tex] which means we can equate:
[tex]p^2+2p=3[/tex].
Subtract 3 from both sides:
[tex]p^2+2p-3=0[/tex].
Then solve for p:
[tex]p^2+2p-3=0[/tex].
[tex](p-1)(p+3)=0[/tex].
So the product of two factors (p-1) and (p+3) is 0 which means at least one of the factors must be 0:
[tex]p-1=0\implies p_1=1[/tex].
Or
[tex]p+3=0\implies p_2=-3[/tex].
Hope this helps.
