Ask a Doubt
Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 10 Answered

find the 20th term of AP whose third term is 7 and 7th term exeeds three times the 3rd term by 2 .also find the n th term.  
Asked by pan2serve | 05 Aug, 2018, 05:19: PM
answered-by-expert Expert Answer
begin mathsize 16px style Here comma straight a subscript 3 space equals space 7 space rightwards double arrow straight a space plus space 2 straight d space equals space 7 space space... left parenthesis 1 right parenthesis and space straight a subscript 7 space equals 3 left parenthesis straight a subscript 3 right parenthesis space plus space 2 space equals space rightwards double arrow straight a space plus space 6 straight d space equals space 3 space cross times space 7 space plus space 2 space equals space 23 rightwards double arrow straight a space plus space 6 straight d space equals space 23 space space..... left parenthesis 2 right parenthesis Subtracting space left parenthesis 1 right parenthesis from space left parenthesis 2 right parenthesis comma space we space get 4 straight d space equals space 16 rightwards double arrow space straight d space equals space 4 Put space straight d space equals space 4 space in space left parenthesis 1 right parenthesis comma space we space get straight a space plus space 2 space cross times space 4 space equals space 7 rightwards double arrow space straight a space equals space minus 1 straight a subscript 20 space equals space straight a space plus space 19 straight d space equals space minus 1 space plus space 19 space cross times space 4 space equals space 75 straight a subscript straight n space equals space straight a space plus left parenthesis straight n space minus 1 right parenthesis straight d space space space space equals negative 1 space plus left parenthesis straight n minus 1 right parenthesis 4 space equals space minus 1 space plus 4 straight n space minus 4 space equals space 4 straight n minus 5 space end style
Answered by Yasmeen Khan | 06 Aug, 2018, 10:58: AM

Application Videos

Concept Videos

Multiple Choice Questions Practice Test
Answered Unanswered My Questions My Answers
CBSE 10 - Maths
1.The mean weight of 9 students is 25 Kg. if one more student is joined in the group, the mean is unaltered. Find the weight of 10th student 2.If the nth term of an A.P is pn+q find its common difference.
Asked by purbashadebnath1980 | 09 Mar, 2024, 12:10: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
find the sum of following 6+13+20+....+97
Asked by deepikaselvam2009 | 20 Feb, 2024, 08:57: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
If the sum of first n,2n and 3n terms of an AP be S1 S2andS3 respectively then p3 S2-S1
Asked by keshavsinghalhapur | 15 Jan, 2024, 10:56: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
which term of the AP 3,8,13,18.....is. 78?
Asked by durgauikey7000 | 08 Dec, 2023, 08:16: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
5,2,-1....-49 is an arithmetic progression so it has blank terms
Asked by shaikhyakub9946 | 30 Nov, 2023, 11:50: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
if m times the m th term of an AP is equal to n times the n th term, show that the (m+n) th term of the AP is zero
Asked by prassanna.j | 13 Nov, 2023, 11:23: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
My Class Videos Tests ₹ Plans Ask a Doubt
Get Latest Study Material for Academic year 24-25 Click here
×