# Systems of equations

This course is a part of Algebra I, a 17-course Topic series from Khan Academy.

Learn how to interpret solutions to systems of linear equations and solve them.

This course contains 7 segments:

Introduction to systems of equations

Learn what "systems of equations" are, what counts as a solution to such a system, and how we can use graphs to solve them.

Equivalent systems of equations and the elimination method

Learn about the elimination method, which is a way manipulate systems of equations in order to solve them algebraically. This is actually very similar to the way we manipulate single equations in order to solve them!

Solving systems of equations with substitution

Learn about the substitution method, which is another way to manipulate systems of equations in order to solve them.

Manipulating expressions with unknown variables

Learn how to rewrite expressions with variables whose values are unknown, by using another information about those variables. For example, given that a+b=0, express a*b in terms of b alone.

Number of solutions to systems of equations

Learn about the possible number of solutions of systems of linear equations. Spoiler: There can be a single solution, zero solutions, or infinite solutions. These different cases define the distinctions between "consistent" and "inconsistent" systems, and between "dependent" and "independent" systems.

Solving any system of linear equations

Use everything you learned so far in order to solve any kind of system of equations!

Systems of equations word problems

Now that we are able to solve any kind of system we are given, it's time to use that knowledge to solve some word problems.

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