The sum of given A.P.1, 4 , 7 , 10 , . . . upto 20 terms is____________ .Your answer

The sum of given A.P.1, 4 , 7 , 10 , . . . upto 20 terms is___________

1.	The sum of given A.P.1, 4 , 7 , 10 , . . . upto 20 terms is____________ .Your answer
Answer» Given AP is 1,4,7,10,.....\xa0In given AP first term a=1, common difference d=3\xa0Since, Sn= n/2[2a+(n−1)d] ....... sum of n terms\xa0Put n=20 for sum of first 20 terms\xa0S20=20/2 [2(1)+(20−1)3]\xa0S20=10[2+57]\xa0S20=590