Answer
28
Work Step by Step
For distinct real numbers $t_0$ to $t_n$ and polynomial functions p and q in $P_n$, $\langle p,q\rangle=p(t_0)q(t_0)+...+p(t_n)q(t_n)$.
Therefore, for this problem, $\langle p,q\rangle=p(-1)q(-1)+p(0)q(0)+p(1)q(1)=3*1+4*5+5*1=28$