1980 AHSME Problems/Problem 11
Problem
If the sum of the first terms and the sum of the first terms of a given arithmetic progression are and , respectively, then the sum of first terms is:
Solution
Let be the first term of the sequence and let be the common difference of the sequence.
Sum of the first 10 terms: Sum of the first 100 terms:
Solving the system, we get , . The sum of the first 110 terms is
Therefore, .
See also
1980 AHSME (Problems • Answer Key • Resources) | ||
Preceded by Problem 10 |
Followed by Problem 12 | |
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