다음 미분방정식의 특수해 $y _ {p}$ 는?

$y''+4y= \sec 2x$

• ①$\displaystyle y _ {p} = \frac{1} {2} \sin 2x \ln \left | \cos 2x \right | + \frac{1} {4} \cos 2x$
• ②$\displaystyle y _ {p} = \frac{1} {4} \sin 2x \ln \left | \cos 2x \right | + \frac{1} {2} x \cos 2x$
• ③$\displaystyle y _ {p} = \frac{1} {4} \cos 2x \ln \left | \cos 2x \right | + \frac{1} {2} x \sin 2x$
• ④$\displaystyle y _ {p} = \frac{1} {2} \cos 2x \ln \left | \cos 2x \right | + \frac{1} {4} x \sin 2x$