Glossary
Converge
A series *converges* if the sum of its terms approaches a finite, specific value as the number of terms approaches infinity.
Example:
The series converges to 2, as its partial sums get closer and closer to 2.
Diverge
A series *diverges* if its sum does not approach a finite, specific value as the number of terms approaches infinity; instead, it grows infinitely large or oscillates.
Example:
If you keep adding terms of , the sum will continue to grow without bound, meaning the series diverges.
Evaluate the limit
The process of finding the specific value that a function or sequence approaches as its input or index tends towards a given point or infinity.
Example:
To determine if a series diverges using the nth term test, you must first evaluate the limit of its general term as n approaches infinity.
Limit notation
A mathematical way to express the value that a function or sequence approaches as its input or index gets arbitrarily close to a certain value, often infinity.
Example:
To describe the behavior of a function as x gets very large, we use limit notation like .
Series
The sum of the terms of a sequence. In AP Calculus BC, this often refers to an infinite sum of terms.
Example:
The expression represents a series, specifically the harmonic series.
nth Term Test for Divergence
A test for infinite series stating that if the limit of the nth term as n approaches infinity is not zero, then the series diverges. If the limit is zero, the test is inconclusive.
Example:
When analyzing the series , applying the nth Term Test for Divergence reveals the limit of the terms is 2, so the series diverges.