@janhardo 

The age of a book is not always an issue. For example, Heck's book, https://staff.fnwi.uva.nl/a.j.p.heck/Maplebook/
is excellent after almost 20 years. Almost all the code still works.
I recommend it (but it contains more advanced material; of course, newer topics are not covered). It has many examples with full solutions.

@mmcdara 

@ecterrab 

My point was just that debugging is more difficult than it used to be long time ago. I know that the regular commands are documented. I was referring to some implementation notes to be used by advanced users and the fact that part of the general Maple functionality is now located in the Physics package.

@gawati2611 

In this case you can simply plot  Re(z)>0, |z| > 1.
But note that inequal also accepts boolean operators, such that the region can be as complicated as you want (see the help pages).

@Preben Alsholm 

Nice catch! I remember that long time ago, such bugs were much easier to detect. Now, there are Maple fundamental functions which are implemented in a strange and undocumented manner. Of course, most of these functions are not designed to be used directly by the user, but it would be nice to know something about them. For example, some of such functions (including a part of the assume facility)  are in the Physics package, where almost everything is redefined.

@mmcdara 

@janhardo It is difficult to learn Maple when the examples involve unknown maths methods.
To be efficient, I suggest to solve first those problems for which the maths is clear for you. After that, your Maple knowledge will be good enough to approch other problems. Keep in mind that when solving a math problem in Maple (for which a direct command does not exist)  you will have to know/read/review the existing methods (or maybe to invent or rediscover them!) .

@janhardo 

@Danial If you are interested in the exact solution, you could rewrite (by hand) the inequality as a system of polynomial inequalities and then call solve or SemiAlgebraic. Unfortunalely Maple is not able to do this automatically.

P.S. In general it is is not possible to visualize inequalities in 3D. Try e.g. 
(x^2+y^2+z^2-1)*(x^2+y^2+z^2-2)<=0.
 

@rameen hamood 

It is easy to write it by hand (which I suppose you should do). Or, execute

LinearAlgebra:-GenerateMatrix([x1+6*x2, -2*x2, -4*x1+2*x2], [x1,x2]);

and select the matrix.
 

@nm You are confusing the OP.  A is a 5x4 matrix, so A.x makes sense and is the column Vector: 
<2298, -531, -160, -503, 579>
 

@nm Your initial ode is 
(2*x+y)/(3-x+3*y^2) dx - dy = 0; # M = (2*x+y)/(3-x+3*y^2), N = -1

It is not exact.

@michalkvasnicka 

For a more robust approach see Acer's answer. But you should be aware than any CAS may fail to solve directly your problem. If you know the maths behind it and the CAS language you have big chances to get a result. If not, it remains to complain about it.

@Fancypants The points are not unique, you are missing a condition.
It's not difficult to give an example, e.g. all Lij equal to 1 or 2.

@Fancypants Initially, all Lij were known. Now you say that some are not known. It's not the same thing!
In your picture, P0, P2, P3 seem to be collinear. If true, the number of needed Lij known could be decreased by 1. In principle this number must be >= 10 for a unique solution, but not any 10 will guarantee the uniqueness. Anyway, in this case a symbolic solution is improbable. If your problem is numeric you have the possibility to use DirectSearch to solve the system.