Chapter 5 - Exponents and Polynomials - 5.3 - Multiplying Polynomials - Problem Set 5.3 - Page 207: 19

$3n^2+19n+6$

Using the Distributive Property and then combining similar terms, the given expression, $ (3n+1)(n+6) ,$ is equivalent to \begin{array}{l}\require{cancel} 3n(n)+3n(6)+1(n)+1(6) \\\\= 3n^2+18n+n+6 \\\\= 3n^2+19n+6 .\end{array}