Find S5 for the sequence 3, 13, 23, 33, 43, 53, 63, 73.A) 43 B) 115 C) 120 D) 225
Accepted Solution
A:
The sequence is 3 , 13 , 23 , 33 , 43 , 53 , 63 , 73 S5 ⇒ The sum of the first 5 terms of the sequence ∴ S5 = 3 +13 + 23 + 33 + 43 = 115
So, the answer is option (B) ========================================================= Another solution: ---------------------------- It is observed that the first number = 3 And each number increased by 10 from its previous number So, the sequence is an arithmetic series. let a ⇒ is the first term of an arithmetic sequence . and d ⇒ is the difference between terms of the arithmetic sequence . So Sn ⇒ is the sum of n terms in the arithmetic sequence .