(a) Compute the sums of the squares of Rows 1-4 of Pascal's Triangle.
Do these sums appear anywhere else in Pascal's Triangle?
(b) Guess at an identity based on your observations from part (a). Your identity should be of the form
(You have to figure out what "something" is.) Test your identity for using your results from part (a).
(c) Prove your identity using a committee-forming argument.
(d) Prove your identity using a block-walking argument.
This question has been posted before but has no answer for c and d. I got the other parts, so only help with c and d.