# math

posted by
**B8**
.

from the expression below, which one is not factorable?

1)x^2+4x+6

2) 3ab^2-16a

3)x^2-441

4)4x^2+19x-5

I thought the answer was 2) b is not in the second part of the equation(the 16a)

Is this correct?

Thanks for checking my work