Respuesta :

Answer:

-5u^3 - 5u^2  + 3.

Step-by-step explanation:

(u^3 + 3u^2 + 3) + (-6u^3 - 8u^2)

= u^3 + 3u^2 + 3 - 6u^3 - 8u^2

= u^3  - 6u^3 + 3u^2 - 8u^2 + 3

= -5u^3 - 5u^2  + 3.