Help.
(3p^2 + 5pq-q^2 ) + (p^2 + 3pq - 2q^2 ) =
3p^2 + p^2 + 5pq + 3pq - q^2 - 2q^2 =
4p^2 + 8pq - 3q^2
27x^3 + 64 this is a difference of two cubes
( 3x + 4) ( ( 3x)^2 - (3x * 4) + 4^2) =
(3x + 4) ( 9x^2 - 12x + 16)