268 views
1 vote
What is the sum of the arithmetic sequence 153, 139, 125, ..., if there are 22 terms? A. 132 B. 154 C. 176 D. 198

1 Answer

4 votes

Answer: 132

Step-by-step explanation

The formula I'll use is

Sn = (n/2)*(2*a1 + d*(n-1))

the variables are

  • n = number of terms
  • a1 = first term
  • d = common difference
  • Sn = sum of the first n terms

In this case we have these values

  • n = 22
  • a1 = 153
  • d = -14 since we go down by 14 each time

So,

Sn = (n/2)*(2*a1 + d*(n-1))

S22 = (22/2)*(2*153 + (-14)*(22-1))

S22 = 132

The first 22 terms of the arithmetic sequence 153, 139, 125, ... sum to 132

User Josh Randall
by
7.9k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories