Answer:
(x+4)(x-7)
Step-by-step explanation:
( x + 4 ) ( x - 7 )
x^2 - 3x - 28
= x^2 + 4x - 7x - 28
= x ( x + 4 ) - 7 ( x + 4 )
= ( x + 4 ) ( x - 7 )