University of Minnesota
University of Minnesota: Math Insight: Multiplying Matrices and Vectors
A clear explanation of how to multiply a matrix by a vector and a matrix by a matrix. A follow-up page provides additional examples.
Khan Academy
Khan Academy: Use Matrices to Transform 3 D and 4 D Vectors
Find the result (both algebraically and graphically) of transforming a vector using a transformation matrix. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
OnlineMathLearning.com
Online Math Learning: Multiply a Vector by a Matrix
Examples, solutions, videos, and lessons to help students learn how to multiply a vector (regarded as a matrix with one column) by a matrix of suitable dimensions to produce another vector. Work with matrices as transformations of...