• Factoring by Pairs


     

         We use factoring by pairs when we have 4 terms in an expression or equation.   You are actually factoring a greatest common factor twice.

     
    ex.     2a2 + 3ac + 2ab + 3bc
           2a2 + 3ac + 2ab + 3bc
             a(2a + 3c) + b(2a + 3c)
             (2a + 3c)(a + b)     		 pair up the four terms
    factor the pairs
    factor the binomials
    FOIL to check answer
    ex.     ax + 2ay + 2bx + 4by
            ax + 2ay + 2bx + 4by
             a(x + 2y) + 2b(x + 2y)
             (x + 2y)(a + 2b)