How do you find the sum of the arithmetic sequence given 8, 3, -2, -7, -12, ....., -57?
Step 1: Find the number of terms
The nth term of an arithmetic sequence is given by
Step 2: Apply the formula for sum:
When dealing with arithmetic series, we will frequently use two formulas to help us find the sum. They are:
Since we know the first term, the last term and the number of terms, we have enough information to use the latter; this one is more efficient and easy to use than the first.
Hence, the sum of this arithmetic sequence is
- Determine the sum of the following sequence:
Hopefully this helps, and good luck!