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If the sum of the first n terms of an AP...

If the sum of the first n terms of an AP is `4n-n^(2)` , what is the first term (note that the first term is `S_(1)`)? What is the sum of first two terms? What is the second term? Similarly, find the 3rd, the 10th and the nth terms

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The correct Answer is:
`S_(1) =3, S_(2) =4; a_(2)=1; a_(3)=-1, a_(10)= -15`
`a_(n) \ 5-2n`
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