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The sum of first n terms of an AP is 4n^...

The sum of first `n` terms of an AP is `4n^2+2n`. Find its `n`th term.

Text Solution

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`S_n=n/2{2a+(n-1)d}`
`4n^2+2n=n/2{2a+(n-1)d}`
`4n^2+2n=a_n+n/2(n-1)d`
`4n^2+2n=a_n+(n^2d)/2-(nd)/2`
`4n^2+2n=n{a-d/2}+d/2n^2`
`a-d/2=2,a-8/2=2`
`d/2=4,d=8`
`a_n+a+(n-1)d`
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