For this case we have the following polynomials:
4x ^ 5 + 6x ^ 3 + 3
3x ^ 3 + x + 9
Adding we have:
(4x ^ 5 + 6x ^ 3 + 3) + (3x ^ 3 + x + 9)
We group in similar terms:
x ^ 5 (4) + x ^ 3 (6 + 3) + x (1) + (9 + 3)
Rewriting we have:
4x ^ 5 + 9x ^ 3 + x + 12
Answer:
4x ^ 5 + 9x ^ 3 + x + 12
option C