Browse · MATH
Printjmc
algebra junior
Problem
Calculate the sum .
Solution
The arithmetic sequence 1, 3, 5, , 17, has common difference 2, so the term is . If , then , so this arithmetic sequence contains 9 terms.
The sum of an arithmetic series is equal to the average of the first and last term, multiplied by the number of terms, so the sum is .
The sum of an arithmetic series is equal to the average of the first and last term, multiplied by the number of terms, so the sum is .
Final answer
81