Double Integral of yx: Solving with k^2*X^2*a^3/6 - Attempt at Solution

[SimpliciusH]

Homework Statement

http://img687.imageshack.us/img687/6092/dvojniinteg3.png

Uploaded with ImageShack.us

The Attempt at a Solution

=k^2*X^2*a^3/6

Is this the correct solution?

 

[gabbagabbahey]

Homework Statement

http://img687.imageshack.us/img687/6092/dvojniinteg3.png

Uploaded with ImageShack.us

The Attempt at a Solution

=k^2*X^2*a^3/6

Is this the correct solution?

No, you are integrating over both y and x, so your answer shouldn't have x in it. Why not show us your steps...

 

[hgfalling]

His x limit of integration includes an x, so I think this is the right answer. I suspect it might be the wrong integral, however. :)

 

[SimpliciusH]

Ok, I'll post the steps... BTW Can I just ask how one writes integrals on forums so those so they aren't a terrible pain to read? :)

@hgfalling: Do you think there was a typo in text or did I make a really dumb mistake?

Edit: I've went to wolfram alpha and got the same result. Should I in the future use similar notation to that accepted by wolfram?

http://img717.imageshack.us/img717/7077/integral2.png

Uploaded with ImageShack.us

 

[SimpliciusH]

@gabbagabbahey: Your signature is most helpfull! :)

 

[tiny-tim]

Hi SimpliciusH!

have an integral: ∫ and try using the X² tag just above the Reply box )

You may have fooled Wolfram, but you can't fool us …

you can't integrate over a variable and then put the variable back in as a limit of integration …

∫₀^kx f(x) dx doesn't make sense.

 

[gabbagabbahey]

Are you sure the integral isn't \int_0^a\int_0^{kx}xy^2dydx? As tinytim said, it is very bad notation to have an integral over x and have x in your integration limits.