This 14-minute video lesson gives a basic overview of U.S. history from reconstruction to the Great Depression. [History playlist: Lesson 3 of 26]

This 15-minute video lesson gives a basic overview of U.S. history from World War II to the Vietnam War. It briefly looks at Hitler, the Cold War, the Bay of Pigs, the Cuban Missile Crisis, and the Space Race. [History playlist: Lesson 4 of 26]

This 18-minute video lesson provides an overview of the Vietnam War. [History playlist: Lesson 9 of 26]

In this 14-minute video lesson Sal weighs in on capitalism and his understanding of when capitalism can potentially undermine innovation, competition and merit. [History playlist: Lesson 12 of 26]

This 7-minute video lesson looks at 2010 IIT JEE Paper 1 Problem 39.

This 7-minute video lesson continues to look at 2010 IIT JEE Paper 1 Problem 39.

This 3-minute video lesson concludes the discussion of 2010 IIT JEE Paper 1 Problem 39.

We've learned about matrix addition, matrix subtraction, matrix multiplication. So you might be wondering, is there the equivalent of matrix division? And before we get into that, let me introduce some concepts to you. And then we'll see that there is something that maybe isn't exactly division, but it's analogous to it.

Sal checks whether the commutative property applies for matrix multiplication. In other words, he checks whether for any two matrices A and B, A*B=B*A (the answer is NO, by the way). Created by Sal Khan.

This 16-minute video lesson shows that a projection onto a subspace is a linear transformation. [Linear Algebra playlist: Lesson 110 of 143]

This 14-minute video lesson shows how to determine the equation for a plane in R3 using a point on the plane and a normal vector.

This 25-minute video lesson introduces the idea of an angle between two vectors.

This 27-minute video lesson provides an example using the orthogonal change-of-basis matrix to find the transformation matrix. [Linear Algebra playlist: Lesson 128 of 143]

This 17-minute video lesson shows how to express a projection on to a line as a Matrix Vector prod. [Linear Algebra playlist: Lesson 61 of 143]

This 15-minute video lesson shows how to find the eigenvectors and eigenspaces of a 2x2 matrix. [Linear Algebra playlist: Lesson 136 of 143]

This 12-minute video lesson provides an introduction to the null space of a matrix and shows that the null space of a matrix is a valid subspace. [Linear Algebra playlist: Lesson 34 of 143]

This 18-minute video lesson shows how to solve a system of linear equations by putting an augmented matrix into reduced row echelon form. [Linear Algebra playlist: Lesson 30 of 143]

This 12-minute video lesson provides another example of solving a system of linear equations by putting an augmented matrix into reduced row echelon form. [Linear Algebra playlist: Lesson 32 of 143]