Question

Can someone please help with integration by parts find the integral of x^2sinpixdx

Answer 1

@satellite73

Answer 2

ack
you have to do it twice

Answer 3

\[u=x^2\\
du=2xdx\\
dv=\sin(\pi x)\\
v=-\frac{1}{\pi}\cos(\pi x)\] is hte first one

Answer 4

Omg

Answer 5

I don't like this already

Answer 6

then you are going to have to do it again

Answer 7

Okay

Answer 8

\[uv-\int v du\] is a start

Answer 9

Someone showed me a different method but we haven't learned it yet so it probably wouldn't be excepted on quiz/test

Answer 10

Okay I'll try and figure it out and I'll let you know what I get in a couple minutes

Answer 11

\[-\frac{x^2}{\pi}\cos(\pi x)+\frac{2}{\pi}\int x\cos (\pi x)dx\]

Answer 12

Okay that's what I got

Answer 13

You can also do this one easy by the table method. Have you learned it yet?

Answer 14

no

Answer 15

kayders?

Answer 16

No, I don't think that's what the other person showed me, I understood it way better though than this

Answer 17

i mean no i have not learned it, but saw it in a movie with olmos

Answer 18

I meant I think

Answer 19

I don't like this method though to many things going on :(

Answer 20

Yes this was it

Answer 21

What I did was I chose x^2 to derive because eventually it becomes zero after deriving enough.. The other part is chosen to be the part I integrate.

Answer 22

Okay

Answer 23

now multiplying across the first line we have our original integral..
You'll notice that if we multiply diagonally though, each line down until we have 2 times the last integral row number we will have our answer taking into account the change in signs every row.

Answer 24

Oh okay

Answer 25

I like that method much more

Answer 26

It's a much more organized approach overall, when it works..

Answer 27

When it works?

Answer 28

When you don't need trig identities or other functional methods...
Take the integral of 1/x(sqrt(x+1))dx

Answer 29

Oh my gosh :O

Answer 30

What calc are you in?

Answer 31

Integral calc

Answer 32

I'm a high school student in calc 1

Answer 33

There are many things I still need to learn lol

Answer 34

I'll try the problem you posted