April 1, 2015

Homework Help: Calc

Posted by UCI Student on Wednesday, May 30, 2012 at 8:15pm.

Hello im trying to integrate tan^3 dx

i have solved out the whole thing but it doesnt match up with the solution..
this is what i did:

first i broke it up into:
integral tan^2x (tanx) dx
integral (sec^2x-1)(tanx) dx

then i did a u substitution
u = secx
du = secxtanx dx (dx = du/secxtanx)

so now i have..
integral (u^2 - 1)*tanx* du/secxtanx
(then the tanx's cancel and then i have a secx with which i re-subsitute u for)

so now i have:
integral (u^2-1)/u
and break it up...
integral u^2/2 - integral 1/u
= integral u - integral 1/u

=u^2/2 - lnabs(u) + c
(and then plug u back in)

(sec^2x)/2 - lnabs(sec^2x) + c
...but it says this is wrong because the anser is actually tan^2x/2 - lnabs(sec^2x) + c

ive done this problem numerous times and i just cant figure out what im doing wrong, any help would be amazing thank you so much!

Answer this Question

First Name:
School Subject:

Related Questions

Calc - Hello im trying to integrate tan^3 dx i have solved out the whole thing ...
Calculus - Silly question here, but I am not getting a certain part in the ...
Calculus - Calc length of arc of y=ln(x) from x=1 to x=2 ---- So far: Definite ...
Calculus - Integration - Hello! I really don't think I am understanding my calc ...
trig sub question - Hello, I have a question concerning trigonometric ...
Calc 121 - How do you integrate using substitution: the integral from 1 to 3 of...
calculus - Integrate: dx/sqrt(x^2-9) Answer: ln(x + sqrt(x^2 - 9)) + C I'm ...
Tan^2 Integrals - I'm having a hard time understanding how to do Integrals ...
Calc 3 - How do I integrate rcos2theta dr? and then I have to plug in the limits...
[Calculus] U-substitution for Integrals - Integrate from 1 to 5 of (3x-5)^5 dx...