Final answer:
The terms 3x^2 and 4xA cannot be combined because they are not like terms.
Step-by-step explanation:
To find the sum of 3x^2 and 4xA, we need to check if the terms can be combined. In this case, the terms cannot be combined because they are not like terms. Like terms have the same variables raised to the same powers. Here, the first term has x raised to the power of 2, while the second term has x raised to the power of 1. Since the powers are different, we cannot combine them. Therefore, the sum of 3x^2 and 4xA cannot be simplified further.