I did no understand simultaneous equations

when programming, please use a decent spacing, else nobody will see an error when an obvious one exists. "pep8".
if i is a variable... ok, no problem we overwrite that ?1????, then please do not redefine it in a loop as a number. (This would have been a second alarm while reusing i...) Nobody does this, so this atypical error cannot be seen at a first glance. In our case this brings the error as follows. After the last i-loop this "global variable" has the value 2, and we try to solve a system of equations, where one of the equation variables is the constant 2. The error message is also misleading.
give a minimal code showing the error, only needed lines of code.
use list comprehension.
do not call a list eqns, when it does not collect equations, but rather entries of a matrix. The solve of these "equations" will be hardly detected with bare eyes as an error.
try to give pointed prints. The show command delivers a mess, is not a good control of the operations.
the two definitions of eqns and xlist are not needed. The wording for xlist is also not proper. Something like X_entries would reflect the provenience, but we do not need this new variable, the matrix X already has the information.
Please understand that these "critics" are just kind advices, at any rate not offensive, in my case, knowing these as i started programming in python would have been a real benefit.
sage: V=var("v", n=9)
sage: P=matrix(V,nrows=3)
sage: X=matrix(SR,3,3,[[0,1,0],[0,0,1],[1,0,0]])
sage: Pdagger=P.transpose()
sage: Xdagger=X.transpose()
sage: Q=X*Pdagger
sage: B=Q.solve_left(X)

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There's a guide for that:
Canon 788SG User Instruction Simultaneous Linear Equations

let c = cory's age now let s = her sisters age now
cory's age now = sisters age + 6 years
=> c = s + 6
4 years ago, cory was 4 years younger ( i.e. c-4) and her sister was 4 years younger (s- 4)
4 years ago cory was 4 times older than her sister
=> c - 4 = 4*(s-4)
We can simplify this to c = 4s - 16 +4 c = 4s - 12
We can then use simultaneous equations to solve the two equations
(i) c = s + 6 (ii) c = 4s - 12
If we multiply both sides of equation (i) by 4 we get (iii) 4c = 4s + 24
We can then subtract equation (ii) from equation (iii) to eliminate the '4s' term => ( 4c = 4s + 24 ) - (c = 4s - 12) => 4c - c = 4s +24 - 4s +12 => 3c = 4s - 4s +36 => 3c = 36 => c = 36/3 => c = 12 => Cory's age now = 12
For clarity: Her sister's age now is of course 6 4 years ago Cory would of been 8 and her sister would of been 2
I hope this helps and good luck! If you have more questions - ask away!
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Many Thanks Don.

The absolutely-best, most-robust, software for solving systems of linear equations is the LINPACK software library.

It was originally written in FORTRAN.

But, see: http://www.greenecomputing.com/apps/linpack/

which indicates that a JAVA version exists.

There are a few routines to solve simultaneous LINEAR equations that are embedded in the Operating system of the calculator.

1. solve(
   
2. Simult(

However if you are looking for the simultaneous equation solver application, you can download it from the TI website. Here is the link

If you need download and install instructions, you will find them here.

Press the [MODE] button 3 times then 1 to enter EQN mode. Then press the right pointing arrow. You can select the degree of the polynomial (2 or 3) or press again the right pointing arrow to select the number of unknowns for simultaneous linear equations( 2 or 3).

The form of the equations are as follows.

Yes. Since there's far too much material for a single post, please refer to the chapter "Matrices" in the Guidebook. If you've misplaced your guidebook, you can download a new one from http://education.ti.com

Hello,

Let us assume you have two simultaneous linear equations :

a_1*x+ b_1*y+c_1=0
a_2*x +b_2*y+c_2=0

where a_1, a_2, b_1, b_2, c_1,c_2 are coefficients (numerical or algebraic).
The problem is to obtain the particular values of the unknowns x and y for which the two equations are both satisfied: If you substitute the particular values of x and y you find in any of the two equations you discover that both equalities are true.

A small system of equations like the one above can be solved by some very simple algorithms (elimination, substitution, combination) which can be carried out by hand.

The solution of large systems of linear equations can be sought by making use of the concepts of matrices (plural of matrix), determinants, and certain rules called Cramer's rules.

Due to its repetitive nature, the algorithm ( a well defined, limited sequence of steps) is suitable for a calculating machine (computer or calculator).

Certain calculators have, embedded in their ROM, a program that solves linear systems of simultaneous equations. Usually you are asked to enter the values of the coefficients a_1, etc. in a set order, then you press ENTER or EXE (Casio) . If a solution exits (not all linear systems have solutions) the calculator displays it.

Hope that satisfies your curiosity.

To view both graphs, the = signs on both y1 and y2 must be contained in black boxes. If you put your cursor over the = sign on the second equation and hit enter, it turns that graph off and you won't be able to see anything but the equation in y1 line. If there is not black box around the = sign of any equation in any of the lines you have typed an equation into, you will not see the graph.