Indefinite Integration

$\log \sec (9 x)-\log \sec (2 x)+\mathrm{c}$, where c is the constant of integration

$\log \sec (9 x)+\log \sec (2 x)+\mathrm{c}$, where c is the constant of integration

$\frac{1}{9} \log \sec (9 x)-\frac{1}{2} \log \sec (2 x)+\mathrm{c}$, where c is the constant of integration

$\frac{1}{9} \log \sec (9 x)+\frac{1}{2} \log \sec (2 x)+\mathrm{c}$, where c is the constant of integration