# Geometric Sequence vs. Exponential Function: What's the Difference?

By Janet White || Published on December 11, 2023
A geometric sequence is a series of numbers multiplied by a constant, while an exponential function is a mathematical expression where a constant base is raised to a variable exponent.

## Key Differences

A geometric sequence involves numbers that are sequentially multiplied by a fixed ratio, creating a series of values. An exponential function, in contrast, is a mathematical equation where a constant base is raised to the power of a variable exponent.
In a geometric sequence, each term is the previous term multiplied by a constant ratio, such as 2, 4, 8, 16, where each term doubles. Exponential functions, however, grow more rapidly since the exponent increases.
Geometric sequences can model scenarios of regular multiplicative growth or decay, exemplified in scenarios like interest calculation. Exponential functions are used to describe more complex growth patterns, like population growth or radioactive decay, where the rate of change increases over time.
While geometric sequences are discrete and consist of individual numbers, exponential functions are continuous, represented as equations and graphed as curves.
The commonality between a geometric sequence and an exponential function is their basis in multiplication, but they differ significantly in their application and representation in mathematical contexts.

## Comparison Chart

### Nature

Discrete series of numbers
Continuous mathematical function

### Growth Pattern

Multiplicative growth by a constant ratio
Growth rate increases as the exponent varies

### Representation

Listed as a sequence of numbers
Expressed as an equation and graphed as a curve

### Application Example

Interest calculation over set periods
Population growth over continuous time

### Commonality

Based on multiplication
Rooted in multiplication, but with varying exponents

## Geometric Sequence and Exponential Function Definitions

#### Geometric Sequence

A sequence of numbers where each term is the previous term multiplied by a constant.
3, 6, 12, 24 is a geometric sequence with a ratio of 2.

#### Exponential Function

Exponential functions are used to model situations where growth or decay accelerates over time.
The value of a car depreciates over time following an exponential function.

#### Geometric Sequence

A numeric pattern where the ratio between consecutive terms is fixed.
The sequence 2, 4, 8, 16 exemplifies a geometric sequence with a ratio of 2.

#### Exponential Function

A mathematical function that grows or decays at a rate exponentially related to its current value.
The decrease in the amount of a drug in the bloodstream over time can be modeled with an exponential function.

#### Geometric Sequence

It’s a finite or infinite series with a constant ratio between terms.
The sequence 7, 14, 28, 56, ..., continues infinitely doubling each term.

#### Exponential Function

An exponential function is a mathematical expression where a fixed number is raised to a variable exponent.
The formula for calculating compound interest is based on an exponential function.

#### Geometric Sequence

It's a series of numbers with a constant multiplicative increment.
In the sequence 5, 10, 20, 40, each term doubles.

#### Exponential Function

It represents a rapid increase or decrease in value, characterized by a constant ratio per unit change in the independent variable.
Population growth in an unrestricted environment can be modeled using an exponential function.

#### Geometric Sequence

Geometric sequences can represent scenarios like repeated doubling or halving.
The sequence 100, 50, 25, 12.5 demonstrates halving in each step.

#### Exponential Function

It's a function where the independent variable appears as an exponent and exhibits exponential growth or decay.
The brightness of a star as perceived from Earth can be expressed as an exponential function of its distance.

## FAQs

#### How do you find the ratio in a geometric sequence?

Divide any term by the preceding term.

#### Can a geometric sequence be decreasing?

Yes, if the constant ratio is between 0 and 1.

#### What does the exponent represent in an exponential function?

The exponent represents the variable that determines the function’s growth rate.

#### Are exponential functions always increasing?

They can increase or decrease, depending on the base and exponent.

#### Can geometric sequences have a negative ratio?

Yes, leading to alternating positive and negative terms.

#### What happens to a geometric sequence as n approaches infinity?

It diverges to infinity or converges to zero, based on the ratio.

#### What is a geometric sequence?

A series where each term is the previous one multiplied by a constant.

#### What is an exponential function?

A function where a constant base is raised to a variable exponent.

#### What role do exponential functions play in biology?

They model population growth and spread of diseases.

#### Why are exponential functions important in economics?

They help model economic growth, inflation, and interest rates.

#### How do you calculate the nth term of a geometric sequence?

Multiply the first term by the ratio raised to the (n-1)th power.

#### What is a real-life example of an exponential function?

Compound interest growth is modeled by an exponential function.

#### What distinguishes an exponential growth from decay?

Growth occurs when the base of the function is greater than 1; decay occurs when it’s between 0 and 1.

#### What is a common mistake in identifying geometric sequences?

Confusing additive patterns with multiplicative ones.

#### How do exponential functions apply in technology?

They model phenomena like computing power growth (Moore's Law).

#### Can exponential functions model oscillations?

Not typically; they represent unidirectional growth or decay.

#### How is an exponential function graphed?

It’s graphed as a continuously curving line, steeply rising or falling.

#### Is a geometric sequence linear or nonlinear?

It’s nonlinear due to its constant multiplicative nature.

#### How does the initial value affect a geometric sequence?

It sets the starting point and scale of the sequence.