the sum of the first 20 terms of an AP with common difference 6 is 1300.write the sequence. find the sum of first n terms of this sequence

Let a  be the first tem of the A.P. Then the  sum of first 20 terms is given byS20=2022a+20-16                        As, Sn=n22a+n-1dAs, the sum of first 20 terms is 1300. Therefore2022a+20-16=1300102a+114=13002a+114=1302a=130-114=16a=162=8.Thus, the required AP has first term 8  and the commom difference 6.So, the sequence is, 8, 14, 20, .........The  sum of first n terms of the AP is Sn=n22a+n-1d=n22×8+6n-1=n26n+10=n3n+5.

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