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HP Forum Archive 20

 graphing/solving with 50gMessage #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 50gMessage #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 50gMessage #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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