Answer:
5x7 + 4x4 - 2x2 - 4x - 10
Explanation:
To add both polynomials, there must be a rearrangement of the terms of both polynomials after removing he parenthesis. The rearrangement is such that items are group together based on the power of x. As such,
(x4 − 9x + 5x7) + (5x − 10 + 3x4 − 2x2)
= x4 − 9x + 5x7 + 5x − 10 + 3x4 − 2x2
Rearranging...
= 5x7 + x4 + 3x4 -2x2 - 9x + 5x - 10
simplifying,
= 5x7 + 4x4 - 2x2 - 4x - 10