Find the sum of the arithmetic progression 1,4,7,10,13,16....1000.
Every third term is removed. Find the sum of the remaining terms.
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I really have no idea how to do sequences, help please? watch
- Thread Starter
- 02-02-2006 00:13
- 02-02-2006 00:23
The arithmetic series is summed using the standard formula.
Then consider the 3rd terms you're removing
7, 16, 25, 34 etc
You're removing another arithmetic series, first term is 7, and the difference is 9. You can easily work out how many terms there are, and so work out it's total.