Please use the hint. Prove this by using combinatorial proof. Hint: Consider thinking about subsets of the set {1, 2, 3, 4, . . . , n−1, n, n+1, n+2};pick the middle number in each possible subset....

Please use the hint.

Prove this by using combinatorial proof.

Hint: Consider thinking about subsets of the set {1, 2, 3, 4, . . . , n−1, n, n+1, n+2};
pick the middle number in each possible subset.

Extracted text: -(":") n+2` 1(п — 0) + 2(п — 1) + 3(п - 2) + 4(п - 3) + ..- + (п - 1)2 + (п - 0)1 %3D