Integration by Substitution

1. Oct 1, 2007

markyp23

1. The problem statement, all variables and given/known data

2. Relevant equations

None. Well, dx=du/cosx

3. The attempt at a solution

I've substituted it in, got new values for the limits but I have u^-1 on the bottom and so can't integrate it from my current knowledge. Basically I'm stuck with:

Integration of u^(-1) du with limits of 1 and 2.

Any help appreciated. Apologies for not being able to work the Latex system.

2. Oct 1, 2007

arildno

Seriously, you haven't encountered the derivative of the natural logarithm yet?

3. Oct 1, 2007

markyp23

I have but I thought it had to be a linear expression to use the natural log. It did cross my mind though - this is what to do, then?

4. Oct 1, 2007

arildno

What do you mean by a "linear expression"??

5. Oct 1, 2007

markyp23

Something of the form (ax+b).

Decided to assume that (u) is in that form and so worked it through. Is ln(2) the final answer?

6. Oct 1, 2007