An automated service for answering common problems from algebra, equations, inequalities, calculus, and matrices. It also plots equations and inequalities.
A resource for functions (integer, elliptic, and number theory functions, among many other kinds) as well as over 10,000 visualizations of selected functions.
From St. Andrews University in Scotland, this site contains illustrated biographies of more than 1,000 mathematicians as well as an index of history topics.