Factoring Trinomials of the form ax 2 +bx+c with a =1. Dr. Marcia L. Tharp. How to factor a trinomial of the form ax 2 +bx+c when a=1. To factor a trinomial means to write it as a product of two binomials. For example x 2 +6x+8= (x+2) (x+4) two binomials