# Introduction to logarithms

1 article
5 videos
3 skills
Learn how we define logarithms and use this definition in order to evaluate various logarithms. For example, evaluate log_2(8) as 3 by realizing that 2^3=8.

### Intro to Logarithms

ARTICLE
Learn what logarithms are and how to evaluate them.

### Intro to logarithms

VIDEO 7:02 minutes
Sal explains what logarithms are and gives a few examples of finding logarithms.

### Evaluate logarithms

PRACTICE PROBLEMS
Evaluate basic logarithmic expressions by using the fact that a^x=b is equivalent to log_a(b)=x.

### Evaluating logarithms (advanced)

VIDEO 4:20 minutes
Sal evaluates log₂(8), log₈(2), log₂(⅛), and log₈(½).

### Evaluate logarithms (advanced)

PRACTICE PROBLEMS
Evaluate advanced logarithmic expressions by using the fact that a^x=b is equivalent to log_a(b)=x.

### Relationship between exponentials & logarithms

VIDEO 1:42 minutes
Sal rewrites 100=10^2 as a logarithmic equation and log_5(1/125)=-3 as an exponential equation.

### Relationship between exponentials & logarithms: graphs

VIDEO 4:10 minutes
Given a few points on the graph of an exponential function, Sal plots the corresponding points on the graph of the corresponding logarithmic function.

### Relationship between exponentials & logarithms: tables

VIDEO 5:59 minutes
Given incomplete tables of values of b^x and its corresponding inverse function, log_b(y), Sal uses the inverse relationship of the functions to fill in the missing values.

### Relationship between exponentials & logarithms

PRACTICE PROBLEMS
Solve various problems that focus on the relationship between a^x=b and log_a(b)=x.