1. **State the problem:** Add the expressions $6a^2 + 9$ and $a + 2$. 2. **Write the expressions:** $$ (6a^2 + 9) + (a + 2) $$ 3. **Remove parentheses and group like terms:** $$ 6a^2 + 9 + a + 2 $$ 4. **Combine like terms:** - The $a^2$ term: $6a^2$ - The $a$ term: $a$ - The constants: $9 + 2 = 11$ 5. **Final simplified expression:** $$ 6a^2 + a + 11 $$ This is the sum of the two expressions.