Question

if sn=3n+1and sn-1=2n-1 then a n is​

Answer 1

Answer:

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Step-by-step explanation:

Given Sum of n terms is S

n

=3n

2

−4n

So Sum of n−1 terms is S

n−1

=3(n−1)

2

−4(n−1)

=3n

2

−6n+3−4n+4

=3n

2

−10n+7

Sum of n terms is equal to sum of n−1 terms plus n

th

term

⟹n

th

term =S

n

−S

n−1

=3n

2

−4n−(3n

2

−10n+7)

n

th

term=6n−7