$\frac{2}{\sqrt{1+k^2}} \tan ^{-1}\left(\sqrt{\frac{1-k}{1+k}} \tan \frac{x}{2}\right)+C$

$\frac{1}{\sqrt{k^2-1}} \log \left(\frac{\sqrt{k+1}+\sqrt{k-1} \tan \frac{x}{2}}{\sqrt{k+1}-\sqrt{k-1}}\right)+C$

$\frac{1}{\sqrt{k^2+1}} \log ^{-1}\left(\frac{\sqrt{k+1}+\sqrt{k-1} \tan \frac{x}{2}}{\sqrt{k+1}-\sqrt{k-1} \tan \frac{x}{2}}\right)+C$

$\frac{1}{\sqrt{k^2-1}} \tan ^{-1}\left(\frac{\sqrt{k-1} \cos \frac{x}{2}+\sqrt{k-1} \sin \frac{x}{2}}{\sqrt{k+1} \cos \frac{x}{2}-\sqrt{k-1} \sin \frac{x}{2}}\right)+C$

$-e^{-3 x}\left(\frac{x^2}{3}+\frac{2 x}{9}+\frac{2}{27}+\frac{3}{25} \sin 4 x+\frac{4}{25} \cos 4 x\right)+C$

$-e^{-3 x}\left(\frac{x^2}{3}-\frac{2 x}{9}+\frac{2}{27}+\frac{3}{25} \sin 4 x+\frac{4}{25} \cos 4 x\right)+C$

$-e^{-3 x}\left(\frac{x^2}{3}+\frac{2 x}{9}+\frac{2}{27}+\frac{3}{25} \sin 4 x-\frac{4}{25} \cos 4 x\right)+C$

$-e^{-3 x}\left(\frac{x^2}{3}-\frac{2 x}{9}+\frac{2}{27}+\frac{3}{25} \sin 4 x-\frac{4}{25} \cos 4 x\right)+C$

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