+ Solve the system of equations
	2x - 2y + z - w = 7
	- x + 4y - 5z + 3w = 1
	x + y - z + w = 4
	-4x + 2y + z - 2w = 6

Commands:
=========

eq1: 2*x-2*y+z-w=7;
eq2: -x + 4*y - 5*z + 3*w = 1;
eq3: x + y - z + w = 4;
eq4: -4*x + 2*y + z - 2*w = 6;

linsolve([eq1,eq2,eq3,eq4],[x,y,z,w]);


Solution:
=========
(%i1) eq1: 2*x-2*y+z-w=7;
(%o1)                        z - 2 y + 2 x - w = 7
(%i2) eq2: -x + 4*y - 5*z + 3*w = 1;
(%o2)                      - 5 z + 4 y - x + 3 w = 1
(%i3) eq3: x + y - z + w = 4;
(%o3)                         - z + y + x + w = 4
(%i4) eq4: -4*x + 2*y + z - 2*w = 6;
(%o4)                       z + 2 y - 4 x - 2 w = 6
(%i5) linsolve([eq1,eq2,eq3,eq4],[x,y,z,w]);
                          116      39        58        69
(%o5)                [x = ---, y = --, z = - --, w = - --]
                          21       7         21        7
(%i6)


Link to solution:
=================
http://maxima-online.org/?inc=r-762047752