Answer
$(2x-3)^2$
Work Step by Step
Since $(a)^2-2(a)(b)+(b)^2=(a-b)^2$ (or the factoring of perfect square trinomials), the given expression, $
4x^2-12x+9
,$ is equivalent to
\begin{align*}
&
(2x)^2-2(2x)(3)+(3)^2
\\&=
(2x-3)^2
.\end{align*}
Hence, the expression $4x^2-12x+9$ is equivalent to $(2x-3)^2$.
