To combine like terms in the expression 3y² + 7y + 9 + 4y² + 6y + 9, you need to group the terms that have the same variable raised to the same power.
1. **Identify Like Terms**: In this expression, the like terms are:
- Quadratic terms: 3y² and 4y²
- Linear terms: 7y and 6y
- Constant terms: 9 and 9
2. **Combine Each Group**:
- For the quadratic terms: 3y² + 4y² = 7y²
- For the linear terms: 7y + 6y = 13y
- For the constant terms: 9 + 9 = 18
3. **Write the Final Expression**: Now, combine all the summed terms to get the final result:
7y² + 13y + 18
So, the combined expression after merging like terms is 7y² + 13y + 18.