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Expand the summation: $\sum_{i=1}^{k+1}i(i!)$

My solution is:

$\sum_{i=1}^{k}i(i!)+k(k+1)$

But I think it is wrong. Please help. Thanks

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Write $i(i!)$ as $(i+1-1)i!=(i+1)!-i!$ before summing.

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    $\begingroup$ thank you. you are amazing. $\endgroup$ – gordon sung Jun 21 '15 at 7:54

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