question again...

i need some guidance to see if im doing this right

-p^3 + 33p + 9

First i did (pq) then i took the derivative to find revenue which i got

-3p^2 +33p + 9p = 0 i need to find largest revenue with this equation

well i keep getting to -p^2 = -11p -3

is this right? or where do i go from here?

Also i had to do a cost equation and had to find what -3p^2 + 18p -265 = 0 i need to find largest weekly profit with this equation

I go to p^2= -88.3 + 6p

Same question here, did i get the right numbers or of i did what do i do to solve?

thank you : )