Chapter 5 - Section 5.3 - Special Products - Exercise Set - Page 367: 8

$5y^2-6y-8$

Using $(a+b)(c+d)=ab+ad+bc+bd$ or the FOIL Method, the product of the given expression, $ (5y+4)(y-2) ,$ is \begin{array}{l}\require{cancel} 5y(y)+5y(-2)+4(y)+4(-2) \\\\= 5y^2-10y+4y-8 \\\\= 5y^2-6y-8 .\end{array}