Question

Q 17 Determine the sum of first 30 terms of the following series.
4, 7, 10, 13, 16, 19, 22,
Ops: A.
O 1378
B.
0 1422
C.
1425
D.
1463​

Answer 1

Answer:

C:-1425

Step-by-step explanation:

This is an arithmetic sequence with a_1 = 4, and a common difference of 3.

The formula for the n-th term is:

a_n = a_1 + (n-1)d

a_n = 4 + 3(n-1) = 3n + 1

So the 30th term is a_30 = 3*30 + 1 = 91

The sum of the 1st n terms of an arithmetic sequence is:

S_n = (n/2)(a_1 + a_n)

So S_30 = (30/2)(4+91) = 95*15 = 1425