İpucu:
$$\int \tan^5xdx=\int \tan^2x\tan^3 x dx=\int (\sec ^2x-1)\tan^3 x dx$$
$$=$$
$$\int \sec ^2x\tan^3 x dx-\int \tan^3 x dx$$
$$=$$
$$\int \sec ^2x\tan^3 x dx-\int (\sec^2x-1)\tan x dx$$
$$=$$
$$\int \sec ^2x\tan^3 x dx-\int \sec^2x\tan x dx+\int \tan x dx$$