Thread: inclusion-exclusion question

2 questions..
Use inclusion-exclusion to find the number of solutions in non-negative integers to:

a) x1 + x2 + x3 + x4 = 56
With conditions
x1 <= 20
x2 >= 16
8 <= x3 <= 38

b) x1 + x2 + x3 + x4 + x5 = 73
x2 <= 30
5<= x3 <= 40
x4 >= 7

I'm having trouble with these harder questions which contain upper and lower bounds and not quite understanding the adding and subtracting of intersections :\
If you could help out it would be greatly appreciated. Thank you very much

Originally Posted by quaz

2 questions..
Use inclusion-exclusion to find the number of solutions in non-negative integers to:

b) x1 + x2 + x3 + x4 + x5 = 73
x2 <= 30
5<= x3 <= 40
x4 >= 7

Similar question answered here: http://www.mathhelpforum.com/math-he...tion-help.html