Factor completely: 2a2 + a − 28
a. (2a − 7)(a + 4)
b. (2a+7)(a-4)
c. (2a-4)(a+7)
d. prime

29 *2 = -56 = 8 * -7

2a^2 + a   - 28   = 2a^2 +8a - 7a - 28
factor by groupintg we have

2a(a + 4) - 7(a + 4)

= (2a - 7)(a + 4)

a

Your answer would be a-  (2a-7)(a+4)!
i always use the foil method (first outside inside last) to check my work.
(2a-7)*(a+4)
2a(a)+2a(4) + (-7)(a)+(-7)(4)
2a62+8a-7a-28
then you have to combine like terms , so 2a^2+a-28.. so its correct!
xx