Curriculum placement
Algebra 2. This describes the skill, not a learner estimate.
Sums of a finite geometric sequence
Calculate finite geometric sums and interpret them in context
Problem types
- Sum a geometric series
- Write a series in sigma notation
- Sum of an infinite geometric series
- Total of a finite geometric series with a fractional or percent ratio
Builds on
- Rules for a geometric sequence
- Linear growth against exponential growth · Useful idea
The total of an exponentially growing quantity over equal steps is a geometric series.
- Properties of logarithms · Useful idea
The number of terms of a geometric series needed to reach a total is found by taking a logarithm.
Leads to
- Using expected value to compare choices · See it applied
An expected value is a sum of each value times its probability, written in sigma notation.
- Solving exponential and logarithmic equations · See it applied
Finding how many terms are needed to reach a total from a geometric sum requires solving an exponential equation.
Related skills
- The binomial theorem · Related idea
Sigma notation writes a sum of terms, and the binomial theorem is a sum whose terms use binomial coefficients.
- Rules for an arithmetic sequence · Related idea
An arithmetic series adds terms that change by a fixed amount, so pairing first and last terms gives its sum. A geometric series adds terms that change by a fixed ratio and uses a different sum rule.
- Building an exponential model · Shared foundations
Open the interactive map to explore lessons and skill connections.