# A particular integral of $(D^{2}-4D+4)y=e^{2x}$ is
$\begin{array}{1 1}(1)\frac{x^{2}}{2}e^{2x}&(2)xe^{2x}\\(3)xe^{-2x}&(4)\frac{x}{2}e^{-2x}\end{array}$