Offline paper
Mathematics · 2018
JEE Main 2018 · 2018-04-08 Offline · Q69
Let A be the sum of the first 20 terms and B be the sum of the first 40 terms of the series 1^2+2 · 2^2+3^2+2 · 4^2+5^2+2 · 6^2+….. If B -2 A =100 λ,…
Let A be the sum of the first $\displaystyle 20$ terms and B be the sum of the first $\displaystyle 40$ terms of the series
$$1^2+2 \cdot 2^2+3^2+2 \cdot 4^2+5^2+2 \cdot 6^2+\ldots . .
$$
If $\displaystyle \mathrm{B}-2 \mathrm{~A}=100 \lambda$, then $\displaystyle \lambda$ is equal to :
Official answer
(2)
$\displaystyle 248$
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