Answer
$16x^2-40x+25$
Work Step by Step
Using $(a+b)^2=a^2+2ab+b^2$, or the square of a binomial, the given expression, $
(4x-5)^2
,$ is equivalent to
\begin{array}{l}\require{cancel}
(4x)^2+2(4x)(-5)+(-5)^2
\\\\=
16x^2-40x+25
.\end{array}