How do you factor the expression #-5a^2 - ab + 6b^2#?

1 Answer

#(5a+6b)(b-a)#

Explanation:

If you multiply the coefficients of #a^2 and b^2# you get #-30#. You need factors of #-30# which differ by #-1#, namely #-6# and 5 which allows you to rewrite the equation as:

#-5a^2-6ab+5ab+6b^2#

You can factorize both pairs separately to give you:

#-a(5a+6b) + b(5a+6b)# which you collect as the answer above