NutshellMath offers explanations to the problems in your textbook, in addition to more general overviews of important math topics - suitable for students using any textbook. Following are some sample explanations for you to view.
Completing the Square and Quadratic Equations
Evaluating Trigonometric Functions of General Angles
Properties of Logarithms
Rational Functions and Their Graphs
Solving Radical Equations
Solving Systems of Equations Algebraically