For A.P. : 7, 11, 15, 19,.... find the sum of first 15 terms. – InterviewSolution

1.

For A.P. : 7, 11, 15, 19,.... find the sum of first 15 terms.

Answer»

A = first term = 7comman ratio d= 11-7= 4n= 15Sn = n/2[2a+(n-1)d]15/2[2*7+(15-1)4]15/2[14+56]15/2[70]15*35=525 Answer

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