Math, asked by abcd718, 1 year ago

In an AP if sum of its first n terms is 3n2+5n and its kth term is 164, find the value of k

Answers

Answered by swaasthika22
38
hope it is correct
n=k
hence k is 27.
Attachments:
Answered by DelcieRiveria
59

Answer:

The value of k is 27.

Step-by-step explanation:

The sum of nth term of the an AP is

S_n=3n^2+5n

S_1=3(1)^2+5(1)=3+5=8

S_2=3(2)^2+5(2)=12+10=22

a_1=S_1=8

The first term is 8.

a_2=S_2-S_1=22-8=14

d=a_2-a_1=14-8=6

The common difference is 6.

The nth term of an AP is

a_n=a+(n-1)d

The kth term of the AP is 164.

a_k=a+(k-1)d

164=8+(k-1)6

164-8=(k-1)6

156=(k-1)6

26=(k-1)

k=27

Therefore the value of k is 27.

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