To put it in the simplest words :
Get rid of the parentheses and add like so:
[tex]2n^3 - 8n^2 + 7 + n^3 + 8n - 9
[/tex]
Combine like terms
2n^3+n^3= 3n^3
-8n^2 remains the same since there are no like terms for it
8n also remains the same
-9+7=-2
Put all of the numbers together
3n^3-8n^2+8n-2
Final answer:
B - the 2nd one
