The author doesn't want the extra solutions showing up on the Internet because it diminishes the value of the book for classroom use.
What I have found is there is usually an answered problem very similar to an unanswered problem. The idea is to have the student solve BOTH problems and compare the answer for one of them. Yes, it's twice as much work!
There won't be any problems that can't be solved with a knowledge of the theory and the use of Matlab. Perhaps "Solving DC and AC Circuits Using Matlab" can help. This may not be what the instructor wants the student to turn in so perhaps it is better to solve by hand and verify by computer.
Also, symbolab.com and desmos.com may be useful. Perhaps the Electrical Engineering videos at Khan Academy.