Question

find the sum of 30 consecutive odd number of which the last is 127

Answer 1

a = 1 d= 2 An = 127 An = a + (n-1)d 127 = 1 + (n -1) 2 126= (n -1)2 n-1 = 126/2 n -1 = 63 n = 64  Sn = n/2{ 2a + (n -1) d} = 32 {2 + 63* 2} = 32 *128 = 4096 ans