Question 731399
Need trinomial on the left side to be a perfect square.

Look at the p term:  -6p, if cut in half would be -3p.  We would expect in the squaring process that we had -3p + -3p, suggesting  constant term of -3 in the binomial.  {{{(p-3)(p-3)=p^2-6p+9}}}, so {{{c=9}}}.