Erin is using this area model to factor 6x^2-7x-20. She puts the term 6x^2 in the upper left corner and -20 in the bottom right corner. The product of the two terms shown in the area model is:
120x^2
-120x
-120x^2
120x
120x^2
the sum of the missing two terms in the area model must be:
-20
6x^2
-7x
The missing two terms she is looking for are:
-13x, 7x
-15x, 8x
-6x, -x
-13x, 7x
the expression factors to:
(3x-4)(2x-5)
(3x+4)(2x-5)
(x-4)(6x+5)
(x+4)(6x-5)