Arithmetic Series Summary Notes
An arithmetic series (AS) is the indicated sum of an arithmetic sequence (AP)
represents the partial sum of a series!
To find a partial sum, just add up the indicated number of terms. If there’s a lot of terms, use this
formula:
Knowing the first term and one other term is key to finding the sum.
If you need to find a term in between two values…
-Subtract the earlier term from the later term
-Divide by the number of terms between the two terms
-And you’ll get your common difference!
-Then, use your common difference and this formula, inserting in the proper
values…
-Then you’ll get the value/term that you’re looking for!
The sum of a series can be written by using a shorthand method called sigma notation (my least favorite
way of writing things lol)
Read this excerpt directly from the notes; it’s not too hard to understand 😊
To write a sigma notation, you’ll want to use the arithmetic sequence formula to find your general nth
term.
For example:
Use sigma notation to write 3+3+9+… for 33 terms.
