https://class.coursera.org/precalculus-003/wiki/Week3
www.m4ths.com
www.examsolutions.net
http://www.hegartymaths.com/
kahnacademy
www.mathisfun.com
www.mathpolis.com
http://en.wikipedia.org/wiki/Portal:Mathematics
http://www.wyzant.com/resources/lessons/math/
http://www.teaching.martahidegkuti.com/shared/lnotes/lecturenotes.html
www.brilliant.org
please add websites and books to the list.
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