---
title: "Logarithmic Functions — AP Calculus Definition & Guide"
description: "Logarithmic functions are the inverses of exponentials, and in AP Calc they power the derivative of ln x, the antiderivative of 1/x, and log differentiation."
canonical: "https://fiveable.me/ap-calc/key-terms/logarithmic-functions"
type: "key-term"
subject: "AP Calculus AB/BC"
---

# Logarithmic Functions — AP Calculus Definition & Guide

## Definition

Logarithmic functions are the inverse of exponential functions. They help us solve for exponents by finding what power we need to raise a base to get a certain value.

## Related Study Guides

- [AP Calculus Multiple Choice Questions](/ap-calc/exam-skills/calculus-multiple-choice-questions/study-guide/eUiZF0wICTO24PQb4erf)

## Review

### Related Terms

- Base: The base of a logarithmic function is the number being raised to a certain power.
- Common Logarithm: The common logarithm uses base 10 and is written as log(x).
- Natural Logarithm: The natural logarithm uses base e (approximately 2.71828) and is written as ln(x).