30x^3y-25x^2y^2-30xy^3

i did all the work but when i got down to

5xy(6x^2-5xy-6y^2)

it took me forever to get the answer

5xy(3x+2y)(2x-3y)

is there a faster way to determine which part of 2y and 3y are negative to get the answer? It took me an hour just to find the answer to this!