How do I factor
-3p^2+84p-288
I wouldn't factor it to get the solutions. I would use the quadratic formula.
p= (-84 +- sqrt (7056+2345)/-6
p= (-84 +- 102.53)/-6
p=31 or p=-3.09
Now factoring..
(3p-93)(p+3.09) check that, of course I rounded in the quadratic...