SATHEE: Sequences and Series 2 Question 9

Sequences and Series 2 Question 9

10. If the sum of the first $2 n$ terms of the AP series $2, 5, 8, \dots$ , is equal to the sum of the first $n$ terms of the AP series $57, 59, 61, \dots$ , then $n$ equals

(2001, 1M)

(a) 10

(b) 12

(d) 13

Objective Question II

(One or more than one correct option)

Show Answer

Answer:

Correct Answer: 10. (c)

Solution:

According to given condition,

$\begin{aligned} S_{2 n} & = S_{n}^{'} \\ \Rightarrow & \frac{2 n}{2} [2 \times 2 + (2 n - 1) \times 3] & = \frac{n}{2} [2 \times 57 + (n - 1) \times 2] \\ \Rightarrow & (4 + 6 n - 3) & = \frac{1}{2} (114 + 2 n - 2) \end{aligned}$

$\begin{array}{lc} \Rightarrow & 6 n + 1 = 57 + n - 1 \Rightarrow \\ ∴ & n = 11 \end{array}$

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Sequences and Series 2 Question 9

10. If the sum of the first $2 n$ terms of the AP series $2, 5, 8, \dots$ , is equal to the sum of the first $n$ terms of the AP series $57, 59, 61, \dots$ , then $n$ equals

Objective Question II

Answer:

इंजीनियरिंग की तैयारी

चिकित्सा तैयारी

एनसीईआरटी पुस्तकें और समाधान

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परीक्षा मंच

नमूना मॉक टेस्ट

सदस्यता

एनसीईआरटी व्यायाम वीडियो समाधान

Sequences and Series 2 Question 9

10. If the sum of the first 2n terms of the AP series 2,5,8,…, is equal to the sum of the first n terms of the AP series 57,59,61,…, then n equals

Objective Question II

Answer:

इंजीनियरिंग की तैयारी

चिकित्सा तैयारी

एनसीईआरटी पुस्तकें और समाधान

महत्वपूर्ण संसाधन

अन्य संसाधन

पाठ्यक्रम

परीक्षा मंच

नमूना मॉक टेस्ट

सदस्यता

एनसीईआरटी व्यायाम वीडियो समाधान

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10. If the sum of the first $2 n$ terms of the AP series $2, 5, 8, \dots$ , is equal to the sum of the first $n$ terms of the AP series $57, 59, 61, \dots$ , then $n$ equals