Chapter 4 - Polynomials - 4.4 Addition and Subtraction of Polynomials - 4.4 Exercise Set - Page 259: 18

$7n^3-5n^2+5n$

By combining like terms, the given expression, $ (5n^3-n^2+4n+11)+(2n^3-4n^2+n-11) $, simplifies to \begin{array}{l} (5n^3+2n^3)+(-n^2-4n^2)+(4n+n)+(11-11) \\\\= 7n^3-5n^2+5n+0 \\\\= 7n^3-5n^2+5n .\end{array}