Cool question (1 Viewer)

[RealiseNothing]

This question is a good way of seeing how much of integration you understand in my opinion.

 

[deswa1]

Why not just integrate by parts?

Edit: Lol- I just realised this was the 2U forum- sorry. Yeah its a good question to test understanding then

 

[Shadowdude]

oh

i see what you did there

 

[Sy123]

Solution

Obviously, if you want to do this yourself then dont look at the solution.

 

[Peeik]

Good question!

 

[Peeik]

Solution

Obviously, if you want to do this yourself then dont look at the solution.

Unless I am mistaken, you had a little boo boo at the end.

 

[Fizzy_Cyst]

Solution

Obviously, if you want to do this yourself then dont look at the solution.

+2?

 

[D94]

Solution

Obviously, if you want to do this yourself then dont look at the solution.

You made an error on the second last line, it should be +2.

 

[RealiseNothing]

Solution

Obviously, if you want to do this yourself then dont look at the solution.

Your last line you've done a silly mistake, otherwise it's correct.

 

[Sy123]

Oops. Yeah I should probably be more careful when doing questions especially when Im uploading on bos

Sorry guise

 

[Carrotsticks]

Maybe if your DP and location didn't have anything to do with me, your silly errors would be eliminated =)

 

[twinklegal19]

yay, I got it!

too bad sy123 beat me to it

Maybe if your DP and location didn't have anything to do with me, your silly errors would be eliminated =)

nice try

 

[RishBonjour]

There was a similar question in a CSSA trial i think. some garden/flower thing.

 

[john-doe]

what if there were no limits? int. by parts then??

 

[Sy123]

Using the integrating with respect to y method:


(though that this bordering on 3U integration)
So it seems that you do need to do integration by parts

You could do the substitution u=ln y
But that leads you to:



So it seems like integration by parts is unavoidable

 

[HeroicPandas]

Whoever thought that int. of lnx.dx is 1/x IS A NOOB (NAH JOKES) LOL

 

[seanieg89]

what if there were no limits? int. by parts then??

Integrate log(t) from t=1 to t=x using the method used for this question, your answer will depend on the variable x. The derivative of this function is log(x) by the fundamental theorem of calculus, so adding an arbitrary constant to your answer gives you the indefinite integral of log x.

(But yeah, parts is more useful to know than this trick.)