Which example correctly demonstrates polynomial addition?(1 point)

To correctly demonstrate polynomial addition, we need to combine like terms from the two given polynomials:

\[
(2x^2 + 6x + 1) + (3x^2 + 3x + 9)
\]

First, we combine the like terms:
- \(2x^2 + 3x^2 = 5x^2\)
- \(6x + 3x = 9x\)
- \(1 + 9 = 10\)

Putting it all together, we get:

\[
5x^2 + 9x + 10
\]

Now let's check the responses:

1. \((2x^2+6x+1)+(3x^2+3x+9)= 5x^4+9x^2+10\) **(Incorrect, wrong degree for \(x^4\))**
2. \((2x^2+6x+1)+(3x^2+3x+9)=5x^2+9x+10\) **(Correct)**
3. \((2x^2+6x+1)+(3x^2+3x+9)=13x^2+9x+10\) **(Incorrect, wrong coefficient for \(x^2\))**
4. \((2x^2+6x+1)+(3x^2+3x+9)=−x^2+3x−8\) **(Incorrect, all terms wrong)**

The correct demonstration is:

**(2x^2+6x+1)+(3x^2+3x+9)=5x^2+9x+10**.