Free and clear online algebra help! | Purplemath

Popular pages

• Free and clear online algebra help! | Purplemath

  Free online lessons, loads of worked examples, clear and practical explainations, and no-nonsense advice. Purplemath is here to help!

• Converting percents to decimals and fractions | Purplemath

  To convert percents to decimals, move the dot two places to the left. To convert percents to fractions, use the fact that percents are out of 100.

• What are the basic trigonometric identities? | Purplemath

  Basic trig identities are formulas for angle sums, differences, products, and quotients; and they let you find exact values for trig expressions.

• What is Descartes' Rule of Signs? How does it work? | Purplemath

  Descartes' Rule of Signs is a time-saving trick for helping you eliminate some of the potential zeroes that are generated by the Rational Roots Test.

• Polynomials: Their Terms, Names, and Rules Explained | Purplemath

  What is a polynomial? This lesson explains what they are, how to find their degrees, and how to evaluate them.

• What are parabolas, their equations, their rules? | Purplemath

  Parabolas are a particular type of geometric curve, modelled by quadratic equations. Parabolas are fundamental to satellite dishes and headlights.