Question

another integration dilema

Answer 1

i like integration dilemmas >:))

Answer 2

\[\int\limits_{?}^{?}(tanx)^4 * (secx)^2 x dx \] find the indefinite integral. Also how do you put in the integration symbol that doesn't include upper and lower bounds?

Answer 3

like i said before erase the "?" lol

Answer 4

ok I didn't see that sorry

Answer 5

hmm first things first...did you know that \((\sec x)^2 = \sec ^2 x?\)

Answer 6

yes it is actually in my book that way I just find it easier to type in that way

Answer 7

i asked because if you let u = \(\tan x\)
then du = \(\sec^2 x\)

so it will be \(\int u^4 xdu\)
however...you still have a lone x there in your equation and you cannot integrate u if there is still an x..are you following?

Answer 8

yes that makes sense

Answer 9

remember i said u = \(\tan x?\)

how do you suppose we isolate x?

Answer 10

the arc tangent of x?

Answer 11

integrate by parts maybe?

Answer 12

then we get integral of tan^5x

Answer 13

i am a bit confused when you say du= ...... was under the impression that du=f'(_) dx. so you have to make the f prime funtion match what you already have

Answer 14

the usub aint magic, it only helps to clarify; but if theres parts that dont u up, its useless

Answer 15

solution is\[(1/5) \tan^5x + c\]

Answer 16

then you typed an extra x

Answer 17

yeah...i didnt see the x :/ i thought it was u-subbable but i think it's possible to integrate by parts after u-sub right...

Answer 18

\[\int\tan^4x\sec^2xdx\]is not the same as what you had

Answer 19

so simple u-sub\[u=\tan x\]try to proceed from there

Answer 20

I think you are right turing test looking at the original I typed in it should have been only "dx" not "xdx" sorry

Answer 21

it's okay, at least it makes the problem a lot easier

Answer 22

for you lol

Answer 23

oh lol =)) then what i have been saying was right until the arctangent-ing of x haha =)))

Answer 24

yup :)

Answer 25

ah..xdx was a nicer problem :)

Answer 26

remember what i said earlier @chrisplusian that let u = \(\tan x\) so du = \(\sec^2 x dx\)

substitute those into \(\int \tan ^4 x sec^2 x dx\)

what will you have?

Answer 27

i agree :) xdx was nicer

Answer 28

I don't know why I don't see these problems easier. When you point out what the u is it is a

Answer 29

piece of cake

Answer 30

don't know why I don't see it myself

Answer 31

hahaha it just takes practice :DD

Answer 32

learning your derivatives well will help you recognize what choices to make for u, so practice that

Answer 33

don't let my simpleton dx stop all you fans of xdx hahahah

Answer 34

ok turing test thank you all for your continued support

Answer 35

I think we could have done that by parts.... if it were xdx
you are welcome :)