Please help me with this question on sequence and series

JEE Class main Answered

Please help me with this question on sequence and series

Asked by aditya.varshney78 | 22 Aug, 2021, 12:45: AM

Expert Answer

The series is 3, 6, 15, 42, 123, ...

Here, first term a₁ = 3 = 3⁰ + 3

Second term a₂ = 6 = 3¹ + a₁

Third term a₃ = 15 = 3² + a₂

Fourth term a₄ = 42 = 3³ + a₃

Fifth term a₅ = 123 = 3⁴ + a₄

Nth term a_n = 3^n-1 + a_{n - 1}

Sum of first n terms = (3⁰ + 3) + (3¹ + a₁) + (3² + a₂) + (3³ + a₃) + (3⁴ + a₄) + ... + (3^n-1 + a_{n - 1})

= (3⁰ + 3¹ + 3²+ 3³ + 3⁴ + ... + 3^n-1) + (a₁ + a₂ + a₃ + a₄ + ... + a_{n - 1})

Answered by Renu Varma | 25 Aug, 2021, 11:34: AM

Answered Unanswered My Questions My Answers

JEE main - Maths

solv

Asked by vishwajeetsinghrajput2018 | 17 Mar, 2024, 12:27: AM

ANSWERED BY EXPERT

JEE main - Maths

solve

Asked by mailtome.aj86 | 26 Feb, 2024, 08:29: PM

ANSWERED BY EXPERT

JEE main - Maths

the value 21/4. 41/8. 81/6..... is

Asked by sabeenashaik575 | 09 Jan, 2024, 09:53: AM

ANSWERED BY EXPERT

JEE main - Maths

solution

Asked by 20sanjaykoley20 | 19 Dec, 2023, 12:57: AM

ANSWERED BY EXPERT

JEE main - Maths

Let S be the sum P the product and R the sum of reciprocal

Asked by kunmunkumar08032008 | 08 Oct, 2023, 01:15: PM

ANSWERED BY EXPERT

JEE main - Maths

Let Tr be the rth term of an AP for r=1,2,3,.... If for some positive integers m, n. We have Tm=1/n and Tn=1/m, then Tmn equals to

Asked by nitinsolanki14102001 | 16 Sep, 2023, 03:01: PM

ANSWERED BY EXPERT

JEE main - Maths

if an= -2/(4n^2)-(16n)+(15), [(4n^2)-(16n)+(15) dis entire thing is the denominator)] then: opt a) a1+a2+....+a10= 20/51 opt b) a1+a2+.....a10=30/51 opt c) a1+a2+......a25=50/141 opt d) a1+a2+.....a25=60/141 Its more than one ans type q, pls tell me a detailed explanation on how to do it as i din understand

Asked by joanmaria916 | 08 Jul, 2023, 04:37: PM

ANSWERED BY EXPERT

JEE main - Maths

There are (4n + 1) terms in a certain sequence of which the first (2n + 1) terms form an A.P. of common difference 2 and the last (2n + 1) terms are in G.P. of common ratio 1/2 If the middle term of both A.P. and G.P. are the same, then find the mid-term of this sequence.

Asked by vishnuramrs07 | 30 May, 2023, 09:05: PM

ANSWERED BY EXPERT

JEE main - Maths

The sum of the common terms of the following three arithmetic progressions. 3,7,11,15,…………,3993,7,11,15,…………,399 2,5,8,11,.........3592,5,8,11,.........359 and 2,7,12,17,……,1972,7,12,17,……,197, is equal to _____ .

Asked by chiyalaxmi28 | 18 Mar, 2023, 10:34: AM

ANSWERED BY EXPERT

JEE main - Maths

AP the sum of integers from 1 to 100 that are devisible by 2 or 5 is

Asked by thakuranurag0987 | 27 Dec, 2022, 02:31: PM

ANSWERED BY EXPERT

Please Login or Sign up to continue!

JEE Class main Answered

Choose Filters

Open In Ask A Doubt App ?

Get in Touch

Call / Whats App