The correct example demonstrating polynomial addition is:
**1.** \((2x^2+6x+1)+(3x^2+3x+9) = 5x^2+9x+10\)
This example correctly sums the corresponding terms of the polynomials.
Here's how the addition works step-by-step:
- Combine \(2x^2\) and \(3x^2\) to get \(5x^2\).
- Combine \(6x\) and \(3x\) to get \(9x\).
- Combine \(1\) and \(9\) to get \(10\).
So the final result is indeed \(5x^2 + 9x + 10\).