Fill in the blank to show what the problem is factored.
x^2 - 3x - 40 = (x - 1.___) (x + 2.___)
4x^2 + 12x - 16 = ( 3.____) (x^2 + 3x - 4)
4x^2 - 9 = (2x - 4.____) ( 5.____ + 3)
a. 8
b. 5
c. 4
d. 3
e. 9
f. 2x
g. 4x
x^2 - 3x - 40 = (x - 8) (x + 5)
4x^2 + 12x - 16 = (2x + 4) (2x - 4)
4x^2 - 9 = (2x - 3) (2x + 3)