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CBSE Class 10 Answered

find the sum of first 15 term of an A.P whose nth term is 3-2n?
Asked by himanshi.updel | 13 Oct, 2018, 11:23: AM
answered-by-expert Expert Answer
begin mathsize 18px style straight S subscript straight n equals straight n over 2 open parentheses 2 straight a plus open parentheses straight n minus 1 close parentheses straight d close parentheses straight S subscript 15 equals 15 over 2 open parentheses 2 straight a plus open parentheses 15 minus 1 close parentheses straight d close parentheses equals 15 open parentheses straight a plus open parentheses 7 close parentheses straight d close parentheses straight a subscript straight n equals 3 minus 2 straight n straight a plus nd minus straight d equals 3 minus 2 straight n straight a minus straight d plus nd equals 3 minus 2 straight n straight a minus straight d space equals space 3 space space and space nd space equals negative 2 straight n....... straight d equals negative 2 so comma space straight a space equals 1...... substitute end style
Answered by Arun | 13 Oct, 2018, 05:55: PM

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CBSE 10 - Maths
find the sum of following 6+13+20+....+97
Asked by deepikaselvam2009 | 20 Feb, 2024, 08:57: PM
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CBSE 10 - Maths
If the sum of the first n terms of an AP be n and the sum of first n terms be m then sum of its (m+n) terms is -(m+n)
Asked by keshavsinghalhapur | 16 Jan, 2024, 08:46: PM
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CBSE 10 - Maths
If the sum of first n,2n and 3n terms of an AP be S1 S2andS3 respectively then p3 S2-S1
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CBSE 10 - Maths
A contract on construction job specifies penalty for delay of completion beyond a certain date as follows Rs. 200 for 1st, Rs. 250 for 2nd, and Rs. 300 for 3rd, so on. If contractor pays Rs. 27,750 as penalty, find the number of days for construction work delayed.
Asked by skandachiranjeevin | 06 Dec, 2023, 07:08: PM
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CBSE 10 - Maths
The sum of the first 7 terms of an AP is 63 and that of its next 7 terms is 161.find the AP
Asked by prassanna.j | 13 Nov, 2023, 11:24: PM
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CBSE 10 - Maths
If the pth term of an AP is 1/q and qth term 1/P. Prove that the sum of the first pqth term is 1/2 (pq + 1).
Asked by latayadav23 | 17 Oct, 2023, 08:39: PM
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CBSE 10 - Maths
if in an A.P. the sum of m terms equal to n and the sum of n terms is equal to m, then prove that the sum of (m+n) terms is -(m+n)
Asked by ananya_monica | 28 Sep, 2023, 07:07: PM
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CBSE 10 - Maths
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CBSE 10 - Maths
find the sum of first 51 term of an AP whose second and third terms are 14 and 18 respectively.
Asked by bkhaiwangkonyak | 07 Mar, 2023, 04:35: PM
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CBSE 10 - Maths
the sum of fourth and eight terms of an A.P is 54 and their product is 665. find the sum of the first thirty terms of an A.P​
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Asked by sakshinde95 | 23 Jan, 2023, 05:50: PM
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