Question

integral of sec (3x) tan (3x) dx

Answer 1

If the derivative of sec x is sec x tan x, what do you think is the integral of sec (3x) tan (3x)? :P

Answer 2

Let u = 3x
du = 3 dx
1/3 du = dx
(1/3)\[\int\limits_{?}^{?}(secu*tanu)du\]
(1/3) secu + c
(1/3) sec(3x)

Answer 3

The (1/3) above the integral is supposed to be next to the integral, multiplying it by 1/3.