WB JEE 2012 | Sequence and Series Question 20 | Mathematics

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WB JEE 2012

MCQ (Single Correct Answer)

-0.33

The value of $$\sum\limits_{r = 2}^\infty {{{1 + 2 + .... + (r - 1)} \over {r!}}} $$

$${e \over 2}$$

$${{3e} \over 2}$$

WB JEE 2025

MCQ (Single Correct Answer)

-0.25

If the sum of ' $n$ ' terms of an A.P. is $3 n^2+5 n$ and its $m$ th term is 164 , then the value of $m$ is

WB JEE 2025

MCQ (Single Correct Answer)

-0.25

The sum of the first four terms of an arithmetic progression is 56 . The sum of the last four terms is 112. If its first term is 11, then the number of terms is

WB JEE 2025

MCQ (Single Correct Answer)

-0.5

If $a, b, c$ are in A.P. and if the equations $(b-c) x^2+(c-a) x+(a-b)=0$ and $2(c+a) x^2+(b+c) x=0$ have a common root, then

$a^2, b^2, c^2$ are in A.P.

$a^2, c^2, b^2$ are in A.P.

$c^2, a^2, b^2$ are in A.P.

$a^2, b^2, c^2$ are in G.P.

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