What Are the Correct u and du Values for These Trig Substitution Problems?

[qzack96]

I really needed some help with these trig substitution problems. Please write the u and du values for each. I'd really really appreciate it !

1) Integrate [e^x/(e^x +1)] dx

2) Integrate [1/(e^2x +1)] dx

3) Integrate [(1+x)/(1+x^2)] dx

Thank you Again !

 

[rock.freak667]

I will give you some hints.

d/dx (e^x)=e^x
d/dx(constant)=0

Can you think of a substitution for the first one?

(a^m)ⁿ= a^mn

what can you do with the second one now?

For the third, try making two integrals from it.

 

[n!kofeyn]

Please write the u and du values for each.

Hi qzack96. I see that this is your first post. Welcome! When you post problems, especially homework problems, please try and show us what work you have done so far. It doesn't matter whether it is complete or correct. Post what you have tried or maybe what you try after following rock.freak667's hints.