미분방정식 $y ''+4y '+13y= \delta \left (t-2 \pi \right)$, $y \left (0 \right) =0$, $y ' \left (0 \right) =0$ 의 해는?

• ①$\displaystyle y= \frac{1} {2} e^ {-3t} \sin 2t u \left (t-2 \pi \right)$
• ②$\displaystyle y= \frac{1} {2} e^ {-3} (t-2 \pi) \sin 2tu \left (t-2 \pi \right)$
• ③$\displaystyle y= \frac{1} {3} e^ {-2t} \sin 3t u \left (t-2 \pi \right)$
• ④$\displaystyle y= \frac{1} {3} e^ {-2} (t-2 \pi) \sin 3tu \left (t-2 \pi \right)$