JEE Math Practice Question
If $$n \ge 2$$ is a positive integer, then the sum of the series $${}^{n + 1}{C_2} + 2\left( {{}^2{C_2} + {}^3{C_2} + {}^4{C_2} + ... + {}^n{C_2}} \right)$$ is :
- A.$${{n(2n + 1)(3n + 1)} \over 6}$$
- B.$${{n(n + 1)(2n + 1)} \over 6}$$
- C.$${{n{{(n + 1)}^2}(n + 2)} \over {12}}$$
- D.$${{n(n - 1)(2n + 1)} \over 6}$$
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