解:當(dāng)??$x=-1$??時,??$x^2+px+q $??的值是??$-5;$??當(dāng)??$x=3$??時,??$x^2+px+q $??的值是??$3,$??
$ 把它們分別代入方程,得$
??$ {{\begin{cases} { {1-p+q=-5①}} \\{9+3p+q=3②}\end{cases}}}$??
由①得,??$q=p-6③$??
$ 把③代入②,得$
??$ 9+3p+p-6=3$??
解得,??$p=0$??
把??$p=0$??代入③,得
??$ q=-6$??
所以??${{\begin{cases} { {p=0}} \\{q=-6}\end{cases}}}$??