Question

Find the sum and choose the correct answer.

2n 3 + 4n 2 - 7 and -n 3 + 8n - 9

Answer 1

2n³ + 4n² - 7
+
-n³ + 8n - 9
______________
n³ + 4n² + 8n - 16

just add / subtract like terms; carry the others along like 4n² and 8n since they don't have like terms

Answer 2

`n^3+4n^2+8n-16`

Explanation:

`2n^3 + 4n^2 - 7 and -n^3 + 8n - 9`

find the sum of the polynomials

`2n^3 + 4n^2 - 7 +(-n^3 + 8n - 9)`

Remove the parenthesis and combine like terms

`2n^3 + 4n^2 - 7 -n^3 + 8n - 9`

`2n^3 -n^3=n^3`

`-7-9=-16`

`4n^2, 8n` have no like terms

`2n^3 + 4n^2 - 7 +(-n^3 + 8n - 9)=n^3+4n^2+8n-16`