JEE Math Practice Question
$$\sum\limits_{r=1}^{20}\left(r^{2}+1\right)(r !)$$ is equal to
- A.$$22 !-21 !$$
- B.$$22 !-2(21 !)$$
- C.$$21 !-2(20 !)$$
- D.$$21 !-20$$ !
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