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graphing/solving with 50g
Message #1 Posted by Robin Shelton on 20 Oct 2011, 3:54 p.m.

Calling all awesome geeks! Calc 3 questions.

How do you graph parametric equations? I.E x(t)= 5cos(t) - cos(5t) y(t)= 5sin(t) - sin(5t)

Also how do you solve multiply equations with multiple variables? I.E. 7x+ 6y+ 9z= 0 5x+ 6y+ 20z= 0 x+ y+ z= 0

Last one! When I integrate the Sq root of [(-12sin(3x))^2+ (12cos(3x))^2 and you are integrating it from 0 to 2(pie)/3 ( I have no pie symbol on the computer... awesome)I get a question mark. But when I integrate it by hand I get 8(pie). Any help would be much appreciated!

      
Re: graphing/solving with 50g
Message #2 Posted by x34 on 20 Oct 2011, 4:15 p.m.,
in response to message #1 by Robin Shelton

1 http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=c01941254&jumpid=reg_R1002_USEN#parametric

2 Use linear solver

      
Re: graphing/solving with 50g
Message #3 Posted by Crawl on 20 Oct 2011, 6:08 p.m.,
in response to message #1 by Robin Shelton

For 2, that's a homogeneous equation which means it has a trivial solution of x=y=z=0.

In general, for systems like that, I would enter them as matrices.

Eg.,

[7 6 9]
[5 6 20]
[1 1 1]

(It's easiest to enter with the Matrix writer)

Then hit 1/x.

Then enter

[0]
[0]
[0]

then multiply.

If the system of equations is not linear, you can use the command MSLV. This is an advantage the 50g has over the TI89, by the way; the TI89 has no built-in function for solving systems of nonlinear equations.

For the last one, it looks to me like the integrand is the constant value 12, so yes, 12 * 2 pi / 3 = 8 pi.

I get the question mark when I evaluate that integral, too. Two ways around it: In approximate mode, you'll get the correct numerical value. To get it exact, when the integral is in level 1 of the stack, instead of hitting EVAL, hit TSIMP. (To simplify trigonometric expressions) It immediately gives 8pi.

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