•  Product Sum II

    These examples will help you to use the product-sum in trinomials (ax2+bx+c)when the b or c value is negative.  Remember sometimes you will have negative factors.

    ex.      x2+5x-14    p= -14
                                s= 5      factors are +7 and -2

                                so factored expression is (x+7)(x-2)

    ex.    x2-4x+3=0    p= 3
                                s= -4     factors are -3 and -1

            (x-3)(x-1)=0   use zero product property to solve

            x= 3 or 1

    ex.   The ALG-I rocket follows the path of h = t2-30t+225.  If h is the height
            of the rocket and t is the time in minutes the rocket is in the air, how long
            would the rocket have traveled for when it came back to earth?

           t2-30t+225=0    p= 225
                                    s= -30   factors are -15 and -15

          (t-15)(t-15)=0      so t=15 minutes