Selesaikan (D^4+2D^2+1)y=x^2cosx

$$( D ^ { 4 } + 2 D ^ { 2 } + 1 ) y = x ^ { 2 } \cos x$$

Selesaikan untuk D (complex solution)

$$\left\{\begin{matrix}D=y^{-\frac{1}{2}}\sqrt{\sqrt{yx^{2}\cos(x)}-y}\text{; }D=-y^{-\frac{1}{2}}\sqrt{\sqrt{yx^{2}\cos(x)}-y}\text{; }D=-iy^{-\frac{1}{2}}\sqrt{\sqrt{yx^{2}\cos(x)}+y}\text{; }D=iy^{-\frac{1}{2}}\sqrt{\sqrt{yx^{2}\cos(x)}+y}\text{, }&y\neq 0\\D\in \mathrm{C}\text{, }&\left(x=0\text{ or }\exists n_{1}\in \mathrm{Z}\text{ : }x=\pi n_{1}+\frac{\pi }{2}\right)\text{ and }y=0\end{matrix}\right.$$