A. y= (2a+7)(a+3)
You can solve this by doing process of elimination. If you look at the factor your trying to group, you can see that the constant is a positive number. And in order to get a positive number, you have to multiply a positive by a positive or a negative by a negative. The other two answer choices have it so that you multiply a negative by a positive.
If you were to check it, just multiply it.
(2a+7)(a+3)
2a^2+6a+7a+21
Combine like terms
2a^2+13a+21
