integrate: ln(x) dx

Question

integrate:  ln(x) dx

anonymous · Answer

You've been reading up on Napier..

amistre64 · Answer

not in about a year :)  i got 5 courses to keep track of this semester

anonymous · Answer

5!

amistre64 · Answer

2 are maths so I only consider it as 3 courses lol

anonymous · Answer

$$x\ln(x)-x$$

anonymous · Answer

$$\Large{\frac{x^2}{2}}$$

amistre64 · Answer

+C

anonymous · Answer

; )

anonymous · Answer

Heaven help u if u miss a constant....

anonymous · Answer

did i remember correctly?

anonymous · Answer

i put a constant. it was 0

anonymous · Answer

This is one of those trick ones...

amistre64 · Answer

$$\int u\ dv\ =\ uv-\int v\ du $$
$$u=ln(x);\ dv=dx$$
$$du = \frac{1}{x}dx;\ v=x$$
$$\int ln(x) dx=x\ ln(x) - \int x\frac{1}{x}dx$$
$$\int ln(x) dx=x\ ln(x) - x +C$$

amistre64 · Answer

you remembered it right :)

anonymous · Answer

it is one that you just memorize because it comes up so frequently. like remembering that the derivative of 
$$\sqrt{x}$$ is 
$$\frac{1}{2\sqrt{x}}$$ without having to reinvent the wheel every time.  integrate by parts to do it but easy to remember

anonymous · Answer

1* ln x...

amistre64 · Answer

true; but i need the int by part practice :)

anonymous · Answer

$$\int\limits lnxdx=\int\limits lnx .1 dx $$
use the ILATE rule

anonymous · Answer

the instructive part is to take the derivative of 
$$x\ln(x)-x$$ and then you get a good illustration of what integration by parts accomplishes

anonymous · Answer

use the ILATE rule

Heh, trick is a rule now..?

amistre64 · Answer

i can never recall ilate for some reason; maybe im just old and senility as taking hold

anonymous · Answer

ILATE?

anonymous · Answer

share

anonymous · Answer

ilate stands for order of prference in integration by parts

amistre64 · Answer

my teacher made me laugh yesterday; she said by the end of term we will be able to do most integrations :)

anonymous · Answer

lol

anonymous · Answer

A countable number....

anonymous · Answer

In India ILATE is rule this is how students are prepared for IIT-JEE

amistre64 · Answer

i tend to perfer to let the math itself do the work instead of cluttering my synapses with memory devices that i can never remember

anonymous · Answer

yeah I would like that too

anonymous · Answer

It is kind of hard to think of until u know it.....

anonymous · Answer

do most integrations!  you will be famous.  rich too.

anonymous · Answer

yeah i used that rule when i was in school
I LATE to class almost every day

amistre64 · Answer

calc ii, and shes going over calc i derivative rules and i was the only one that could answer how to do any of them

anonymous · Answer

lol

amistre64 · Answer

she said, its probably been awhile since you did derivatives; and I was like I just did some yesterday ...

anonymous · Answer

I heard that most calc 2 students wish they had paid more attention in calc1

amistre64 · Answer

now i gotta buy the "textbook" in order to do all the homeworks that count as a grade ....

amistre64 · Answer

i never understood why i should do practice problems for something i already know how to do ..

anonymous · Answer

U have to pass homeworks and exam?

amistre64 · Answer

exams and tests are no problem; the homework is simple enough, but why make it mandatory?  if your not going to be responsible enough to do the work if you need it, then you deserve to be docked

anonymous · Answer

I had 4 times a year home and a formula which basically meant u couldnt get a 1 without doing the home stuff, only a 2

amistre64 · Answer

yep

amistre64 · Answer

if the books like less than $50 online, but $50 or $.05 is all the same when you aint got $.05

anonymous · Answer

look harder

amistre64 · Answer

i might be able to use the tutoring centers copy to copy down the problems which seems to be the route ill take :)

anonymous · Answer

trade in some medals

anonymous · Answer

what text are you using?

amistre64 · Answer

.... but then medals would be worth something and the price would go up and there would be chaos in ireland over the price of potatoes... i dont think i can have that on my conscience, i mean, if i had one that is lol

anonymous · Answer

anton? stewart? shaum's outline?  something goofy?

anonymous · Answer

The nu "library" is quite good...:-)

amistre64 · Answer

i forget the name, the sillybus is all the way back in the car that is like 1.5 miles away

amistre64 · Answer

its got a violin in the front if that helps

anonymous · Answer

yes what edition?

amistre64 · Answer

6th or 7th i think

anonymous · Answer

yeah all you had to do is say "violin" i knew it

amistre64 · Answer

thatd be great :)  thnx

anonymous · Answer

Would u like the solutions manual?

anonymous · Answer

let me know if it is 6e or 7e.  of course they are identical, but the problems maybe be slightly off

anonymous · Answer

you googled violin calculus book lol!

amistre64 · Answer

lol, i did :)