Question

The sum of n terms of an A.P. is 3n² + 5n, then 164 is its
A. 24th term
B. 27th term
C. 26th term
D. 25th term​

Answer 1

Answer:

b)27th term

Step-by-step explanation:

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Answer 2

Answer:

Given :

Sum of n terms = 3n^2 + 5n

$S1 = 3( {1)}^{2} + 5(1) = 3 + 5 = 8$

$S2 = 3( {2)}^{2} + 5(2) = 12 + 10 \\ = 22$

$S3 = 3 {(3)}^{2} + 5(3) = 27 + 15 \\ = 42$

S1 = 8

S2 = 8 + x = 22

=> x = 14

S3 = 8 + 22 + x = 42

=> x = 12

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