If the sum of n terms of an A.P. is , then its nth term is
(a) 4n − 3
(b) 3n − 4
(c) 4n + 3
(d) 3n + 4
Answers
Answered by
14
Answer:
nth term is 4n + 3
Among the given options option (c) 4n + 3 is correct.
Step-by-step explanation:
Given :
Sn = 2n² + 5n ………..(1)
On Putting n = 1 in eq 1,
S1 = 2(1)² + 5 × 1
S1 = 2 + 5
S1 = a1 = 7
On Putting n = 2 in eq 1,
S2 = 2(2)² + 5 × 2
S2 = 2 × 4 + 10
S2 = 8 + 10
S2 = 18
⇒ a2 = S2 – S1
⇒ a2 = 18 – 7
⇒ a2 = 11
Common Difference ,d = a2 - a1
d = 11 - 7
d = 4
By using the formula ,nth term , an = a + (n - 1)d
an = 7 + (n –1) × 4
an = 7 + (n –1)4
an = 7 + 4n - 4
an = 4n + 3
Hence, nth term is 4n + 3
HOPE THIS ANSWER WILL HELP YOU….
Answered by
28
Given:
To find:
nth term of AP
Solution:
For n = 1
For n = 2
We know that,
Option: c) 4n+ 3
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