Which example correctly demonstrates polynomial addition? (1 point) (2x ^ 2 + 6x + 1) + (3x ^ 2 + 3x + 9) = 5x ^ 2 + 9x + 10; (2x ^ 2 + 6x + 1) + (3x ^ 2 + 3x + 9) = 5x ^ 4 + 9x ^ 2 + 10; (2x ^ 2 + 6x + 1) + (3x ^ 2 + 3x + 9) = - x ^ 2 + 3x - 8; (2x ^ 2 + 6x + 1) + (3x ^ 2 + 3x + 9) = 13x ^ 2 + 9x + 10

To perform polynomial addition for the given example, we combine like terms from the two polynomials:

1. \( (2x^2 + 6x + 1) \)
2. \( (3x^2 + 3x + 9) \)

Now, let's add the corresponding terms:

- For \( x^2 \) terms: \( 2x^2 + 3x^2 = 5x^2 \)
- For \( x \) terms: \( 6x + 3x = 9x \)
- For the constant terms: \( 1 + 9 = 10 \)

Putting it all together, we get:
\[ (2x^2 + 6x + 1) + (3x^2 + 3x + 9) = 5x^2 + 9x + 10 \]

So the correct example that demonstrates polynomial addition is:

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