The sum of first, third and seventeenth term of an ap is 216.find the

1.	The sum of first, third and seventeenth term of an ap is 216.find the first 13th term
Answer» 936 nth term of an A.P whose starting term is "a" and common difference is "d"is an = a+(n-1)d1st term = a 3rd term =a+2d 17th term = a+16dAccording to question\xa0a+a+2d+a+16d=2163a+18d=2163(a+6d) = 216a+6d= 216/3a+6d= 72Sum of "n" terms in an AP = n(2a+(n-1)d)/2Sum of thirteen terms = 13(2a+12d)/2 =13(a+6d) = 13*72 = 936 936

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