Answer:
(x+7) (x-4)
Explanation:
x^2 + 3x - 28 = 0
a = 1
b= 3
c= -28
a x c = -28
Find two terms that added equal b, and multiplied equal c.
-4 + 7 = 3
-4 * 7 = -28
Replace the middle term:
x^2 - 4x + 7x - 28 = 0
Group and factor
(x^2 - 4x ) (7x - 28 )
x (x - 4 ) 7 (x -4)
Rewrite
(x+7) (x-4)
