The question "If the sum of nth term of an ap is define as sn=3n2+4 then find the nth term" is taken from class-10 chapter is Arithmetic Progressions Mathematics English-Medium NCERT-Book and related topic is Sum Of N Term Of A.P.. If the sum of nth term of an ap is define as sn=3n2 4 then find the nth term - Questions Bank is from NCERT Solutions class 10 English-Medium subject Mathematics chapter- Arithmetic Progressions Questions bank Students need stored questions answers as questions banks which can be used anytime anywhere as we can't learn so many ncert solutions.
NCERT-Book ➧ class-10 ➧ Mathematics ➧ English-Medium ➧ Arithmetic Progressions ➧ Sum Of N Term Of A.P.
Question:
If the sum of nth term of an A.P. is define as Sn = 3n2 + 4 then find the nth term?
Source:www.questionsbanks.com Last updated: 2022-10-11 23:08:17
Answer:
Given that : Sn = 3n2 + 4
Now Putting n = 1
S1 = 3(1)2 + 4
= 3 + 4
= 7
Putting n = 2
S2 = 3(2)2 + 4
= 3 x 4 + 4
= 12 + 4
= 16
a1 ≠ S1 ≠ 7
∵ a1 = S1 - S0 Here S0 ≠ 0
S0 = 3n2 + 4 ⇒ 3(0)2 + 4 ⇒ 0 + 4 = 4
Using an = Sn - S(n - 1)
a1 = S1 - S0
= 7 - 4
= 3
a2 = S2 - S1 [ using formulla an = Sn - S(n - 1) ]
= 16 - 7
= 9
d = a2 - a1 ⇒ 9 - 3 = 6
an = a + (n -1)d
= 3 + (n - 1) 6
= 3 + 6n - 6
= 6n - 3
Hence nth term is 6n - 3 Answer
Second Method :
Given that : Sn = 3n2 + 4 ................ (i)
Replace n by (n - 1)
We have : Sn - 1 = 3(n - 1)2 + 4
⇒ Sn - 1 = 3(n2 - 2n + 1) + 4
= 3n2 - 6n + 3 + 4
= 3n2 - 6n + 7 ......................... (ii)
an = Sn - S(n - 1)
= 3n2 + 4 - (3n2 - 6n + 7 )
= 3n2 + 4 - 3n2 + 6n - 7
= 6n - 3 Answer
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View AnswerAll chapters of NCERT Book as ncert solutions have exercise questions, textual questions and so many addtional questions like short answered questions, long answered questions and very long questions, here we included all types of questions answers format that need for a students and other stock holders like teachers and tutors. If the sum of nth term of an ap is define as sn=3n2 4 then find the nth term - Questions Bank is from NCERT Solutions class 10 English-Medium subject Mathematics chapter- Arithmetic Progressions Questions bank
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