Chapter 4 - Polynomials - 4.5 Multiplication of Polynomials - 4.5 Exercise Set - Page 269: 44

$a^2-1.2a+0.32$

Using $(a+b)(c+d)=ac+ad+bc+bd$ or the product of $2$ binomials, the given expression, $ (a-0.4)(a-0.8) $, is equivalent to \begin{array}{l}\require{cancel} a(a)+a(-0.8)-0.4(a)-0.4(-0.8) \\\\= a^2-0.8a-0.4a+0.32 \\\\= a^2-1.2a+0.32 .\end{array}