Thanks you guys, it's pretty amazing what I've just learned about maple only by reading your answers.
Actually I prefer acer's workaround with map+isolate as this is the one I can explain most easily to my students.

So, keep it going! ;-)
Rainer

@Carl Love 

Thank you very much!

Could you please give a litlle bit of insight into your solving strategy?
It's obviously working, but I have no clue how this could be easier for MAPLE to solve.

Rainer

Thank you for all your helpful answers.
I'm going to study the benefits of using Matrix instead of matrix soon.

Regards
Ben

Thanks to all who answered!

Rainer