Algebra-1

Question Analysis
This question tests the student's ability to combine like radicals.

Key Concept Explanation
The key concept here is the property of combining like terms, which applies to radicals as well.

Step-by-step Solution
1. Identify the like radicals: $$3\sqrt{7}$$ and $$4\sqrt{7}$$
2. Add the coefficients: $$3 + 4 = 7$$
3. Write...