Answer
$64x^2+48x+9$
Work Step by Step
Using $(a\pm b)^2=a^2\pm2ab+b^2$ or the square of a binomial, the square of the given expression, $
(8x-3)^2
,$ is
\begin{array}{l}\require{cancel}
(8x)^2+2(8x)(3)+(3)^2
\\\\=
64x^2+48x+9
.\end{array}