The derivative of sec(x) is sec(x)tan(x), but I believe the integral is
This is my first post here on mathhelpforum, anyways.
I was gone 2 days from class, and we started doing integrals with trig substitutions. I CANNOT for the life of me get one of these right. To be honest, I'm getting extremely frustrated.
Here is a picture of one of the problems. (I don't know how to use the math software.)
Here's what I'm trying.
I'm using the trig property (1 + tan^2 = sec^2)
I then did
x = 3tan(x)
so dx = 3sec^2(x)
And from there, after substiting x and replacing dx with 3sec^2(x), I simplified it to the integral of sec of x, which I thought was sec(x)tan(x), however, that's not even close to the answer in the back.
I really need help on this,