1. (3x + 5) + (2x + 7)

2. (4x² + 3x - 1) + (2x² - 5x + 6)

3. (7y - 4) + (3y + 9)

4. (x² + 2x + 3) + (3x² - x - 2)

5. What is the sum of (2x² + 3x + 1) + (x² - 2x + 4)?

6. Which expression equals (5a² - 3a + 2) + (2a² + 4a - 1)?

7. What is (3m³ + 2m - 5) + (m³ - 4m + 3)?

8. A rectangle has a length of (2x + 3) units and a width of (x + 5) units. Another rectangle has a length of (x + 1) units and a width of (3x + 2) units. Write and simplify an expression for the sum of their perimeters.

9. Add the three polynomials: (x² + 2x + 1) + (2x² - 3x + 4) + (x² + x - 2)

10. Explain in your own words how to add polynomials. What is the key rule to remember?