April 17, 2014

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 - Calc length of arc of y=ln(x) from x=1 to x=2 ---- So far: Definite ...
Integral calculus - Please do help solve the followings 1) Integrate e^4 dx 2) ...
calculus (check my work please) - Not sure if it is right, I have check with the...
calculus - 1) Integrate Cos^n(x) dx 2) Integrate e^(ax)Sinbx dx 3) Integrate (...
Integration - Intergrate sec^3(x) dx could anybody please check this answer. ...
calculus 2 - Justify, with a written explanation or a mathematical reasoning ...
Integral calculus - Please can anyone help with the following problems - thanks...
Calc - Problems, once again. 1. Compute the average value of: f(x} = x/(x+3) ...
calculus - find dy/dx y=ln (secx + tanx) Let u= secx + tan x dy/dx= 1/u * du/dx ...