Non Linear Equations without the Matrix

11102015, 08:21 PM
Post: #1




Non Linear Equations without the Matrix
Hello to anyone, first of all I am new in this forum and I recently got my HP Prime. I am using it to study functions with many variables. Right now I am with the topic of Max and Minimum values with restrictions. So after making the derivatives. I get stuck because I do not know how to find the values that will make those values 0 . So please anybody knows how to use the calculator in those aspects.
Example: F(x,y,z,λ)= xyzλ(2x+3y+4z90) Derivatives Fx=yz2λ=0 Fy=xz3λ=0 Fz=xy4λ=0 Fλ=2x3y4z90=0 So I need to find the Xs,Ys,Zs and λs that make those values 0. So that would be it and any help I will appreciate it. 

11102015, 08:31 PM
Post: #2




RE: Non Linear Equations without the Matrix
In CAS view:
purge(x,y,z,l); f:=x*y*zl*(2*x+3*y+4*z90) fx:=diff(f,x); fy:=diff(f,y); fz:=diff(f,z); fl:=diff(f,l); solve({fx=0,fy=0,fz=0,fl=0},{x,y,z,l}); Graph 3D  QPI  SolveSys 

11102015, 08:38 PM
Post: #3




RE: Non Linear Equations without the Matrix
Thank you so much for the quick response.
Greetings from El Salvador and I appreciate this forum exist. 

11122015, 07:22 PM
Post: #4




RE: Non Linear Equations without the Matrix
Han,
What am I doing wrong? When I solve this problem in Xcas I get: [[0,30,0,0],[45,0,0,0],[0,0,45/2,0],[15,10,15/2,75/2]] When I solve this problem on the prime (CAS approx) I get: {[(y+10)/(2*z15),(2*z^26*l+45*z)/(2*l*z15*l),(y*z+2*l)/(2*l*z15*l),(3*y^216*l+90*y)/(2*l*z15*l)],[(y+10)/(2*z15),(2*z^26*l+45*z)/(2*l*z15*l),(y*z+2*l)/(2*l*z15*l),(3*y^216*l+90*y)/(2*l*z15*l)]} On the Prime (CAS exact) I get empty brackets []. It's the same on the simulator and handheld. road 

11132015, 06:58 AM
(This post was last modified: 11132015 07:03 AM by parisse.)
Post: #5




RE: Non Linear Equations without the Matrix
This is probably because something has been fixed in Xcas since the last firmware was released.


11132015, 12:20 PM
Post: #6




RE: Non Linear Equations without the Matrix
Thank you parisse. I for one am looking forward to that enigmatic future firmware release.
road 

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