Thread: Verify the following

could someone please give me some hints about how to prove this?

sorry, i thought it worked when i previewed ... i'm not sure how to put it in code, but here's a picture

any help would be much appreciated

not a single person can help?

Originally Posted by BlinkyBoo

not a single person can help?

Suppose that are positive integers such that .
Further, suppose that we have blue balls and red balls.
Now we put the balls all together in a box from which we randomly choose balls.
Surely you can see that we can choose from blue balls.
That is all that summation says.

i'm not sure how that's proving it <:\