Question

Find the sum of the first 30 terms of an Ap series with T1=7n-5

Answer 1

Answer:

first term means n =1 (a)

a = 7 - 5 = 2

a2 = 14-5 = 9 (n = 2)

common difference = a2 - a = 9 - 2 = 7

Sum of n terms of AP = n/2 [2a + (n-1) d]

Sum of first 30 terms = 30/2 [ 2(2) + (30 - 1) 7]

= 15 (4 + 203)

= 15 x 207

= 3105

Hope this helped. Good luck!