Help on a math problem:

[Buick355]

I've been working on this conics problem for over an hour. Just by looking at it I know it's an ellipse. I just can't seem to get rid of the xy term (with the axis rotation formula) so I can pull out a clean ellipse equation to graph.

29x^2-48xy+49y^2-12√169x-8√169y=0

Here's what I have so far

tan2ϑ=48/20


cosϑ=5√26/26


sinϑ=√26/26


x=5√26/26 x’-√26/26 y’


y=√26/26 x’+ 5√26/26 y’

So after a full page of plugging in the x and y term with the x' and y' and foiling and expanding I cannot seem to get rid of the xy term. I know it's probably some little algebraic or computational mistake somewhere, but I can't seem to catch it.

[HarrisonTX]

76^4

[71chevellejohn]

42

[Buick355]

76^4

The answer should be in the form of a ellipse equation (translated to an x'y' coordinate system)

[T.J.]

2+2=4?

[Buick355]

You guys have failed me.

[HarrisonTX]

You guys have failed me.

Brother, what did you expect? X=.. ah screw it.

[Buick355]

I expect you guys to do my schoolwork for me, DUH!! This math ain't gonna solve itself!!

[Leah]

42,79

[T.J.]

I just don't understand...even if you built rocketships for a living, you would never need some crazy shit like that.

[terminator03]

10000000000000000000000000000000000000000000000000 00000000000

[Nash B.]

Just to be clear: is it sqrt(169x) and sqrt(169y) or sqrt(169) * x and sqrt(169) * y?

I just don't understand...even if you built rocketships for a living, you would never need some crazy shit like that.

Riiiiiiight.

[helosailor]

Best I can do for ya, seeing as how I'm in remedial algebra...

http://www.wolframalpha.com/input/?fp=1&i=29x^2-48xy%2b49y^2-12%E2%88%9A169x-8%E2%88%9A169y%3d0&_=1300937568386&incTime=true

[Buick355]

sqrt(169) * x and sqrt(169) * y

This.

[Buick355]

Best I can do for ya, seeing as how I'm in remedial algebra...

http://www.wolframalpha.com/input/?fp=1&i=29x^2-48xy%2b49y^2-12%E2%88%9A169x-8%E2%88%9A169y%3d0&_=1300937568386&incTime=true

Yeah, I already tried that site, LOL. I mostly just need help getting rid of that pesky xy term. When you translate it into the xprime yprime coordinate system the xy term is supposed to disappear leaving you a nice clean Y^2/a^2-x^2/b^2=1 equation. My problem is getting to a form where the xy's cancel and the rest combines. Once you foil and expand everything it gets ridiculous.