Chapter 5 - Section 5.3 - Special Products - Exercise Set - Page 367: 34

$16-9y^2$

Using $(a+b)(a-b)=a^2-b^2$ or the special product of the sum and difference of like terms, the product of the given expression, $ (4-3y)(4+3y) ,$ is \begin{array}{l}\require{cancel} 4(4)-3y(3y) \\\\= 16-9y^2 .\end{array}