Question 768889
Three of our given points are zeros, so

{{{p(x)=a(x+3)(x+1)(x-1)}}}

where {{{p(-2)=-1}}}

which tells us that

{{{a(-2+3)(-2+1)(-2-1)=-1}}}


leading to {{{a=-1/3}}}

{{{p(x)=(-1/3)*(x+3)(x+1)(x-1)}}}