Step-by-step explanation:
you can always combine terms with the same base term and exponent.
I always recommend to sort the different categories and sequence them, with the highest exponent first.
(g² - 4g⁴ + 5g + 9) + (-3g³ + 3g² - 6)
-4g⁴ + g² + 5g + 9 - 3g³ + 3g² - 6
-4g⁴ - 3g³ + 4g² + 5g + 3
I always compare this with a merger of two galaxies. there are just a few actual collisions and mergers of individual star systems and bodies. mostly the different bodies just mix together into a new, larger galaxy.
