8. Sequences and Series
hard

माना $3,7,11,15, \ldots, 403$ तथा $2,5,8,11, \ldots$ $404$ दो समान्तर श्रेढ़ियाँ है तो इनमें उभयनिष्ठ पदों का योग है .............

A

$6696$

B

$6697$

C

$668$

D

$6699$

(JEE MAIN-2024)

Solution

$3,7,11,15, \ldots ., 403$

$2,5,8,11, \ldots ., 404$

$\operatorname{LCM}(4,3)=12$

$11,23,35, \ldots . \text { let }(403)$

$403=11+(n-1) \times 12$

$\frac{392}{12}=n-1$

$33 \cdot 66=n$

$n=33$

$\operatorname{Sum} \frac{33}{2}(22+32 \times 12)$

$=6699$

Standard 11
Mathematics

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