Mathematics · 2026
JEE Main · 28 January 2026, Shift 1 · Q15
The value of Σ_k=1^∞(-1)^k+1((k(k+1))/(k!)) is
The value of $\displaystyle \sum_{k=1}^{\infty}(-1)^{k+1}\left(\frac{k(k+1)}{k!}\right)$ is
Official answer
From NTA’s final answer key for this paper.
(1)
$\displaystyle 1$/e
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JEE Main 2026 Mathematics question, with the answer from NTA’s final answer key. Where our answers come from.