How to factorize a ^ 2 + 2ab-3a-3b How to group and decompose a ^ 2 + 2ab-3a-3b

How to factorize a ^ 2 + 2ab-3a-3b How to group and decompose a ^ 2 + 2ab-3a-3b

a^2+ab-3a-3b
=a(a+b)-3(a+b)
=(a+b)(a-3)