Explanation:
1. (4m² - 1.5m + 2) + (9m - 2m³ + 2m)
= 4m² - 1.5m + 2 + 9m - 2m³ + 2m
= 4m² + (-1.5m + 9m + 2m) + 2 + 2m³
= 4m² + 9.5m + 2 + 2m³
= 2m³ + 4m² + 9.5m + 2
2. (-3y + 2y² - 6) + (3y + 4y² + x)
= -3y + 2y² - 6 + 3y + 4y² + x
= (-3y + 3y) + (2y² + 4y²) - 6 + x
= 0y + 6y² - 6 + x
= 6y² - 6 + x