Answer:
The correct answer for the sum is : n^{3} + 4n^{2} + 8n -16
Step-by-step explanation:
We start by adding each n term, n3 with n3 and the same with n2, n and then numbers
\((2n^{3} + 4n^{2} -7 ) + ( -n^{3} + 8n -9)\)
(2-1)n^{3}
(4+0)n^{2}
(8+0)n
(-7-9)
\(n^{3} + 4n^{2} + 8n -16\)
