Q 68/75 If the sum of first 2n terms
of the A.P. 2, 5, 8,...., is equals to the
sum of first n terms of the A.P. 57, 59,
61,..., then n equals
Answers
Answered by
1
Answer:
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Answered by
2
Answer:
The sum of first 2n terms of 2,5,8,... is
=
2
2n
[2(2)+(2n−1)(3)]
=n(6n+1)
The sum of n terms of 57,59,61,... is
=
2
n
[2(57)+(n−1)(2)]
=n(56+n)
Also, n(6n+1)=n(56+n)
⇒6n+1=56+n
⇒5n=55
⇒n=11
Step-by-step explanation:
Hope it's helpful..
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