Other
Platonic Realms: Conic Sections
A proof to show that the square root of two is an irrational number, followed by a shorter and even more beautiful proof.
Khan Academy
Khan Academy: Quadratics by Taking Square Roots
Solve quadratic equations of the form (x+a)^2-b=0. These can be solved using square roots. For example, solve (x-5)$2-4=0.
Help Algebra
Help algebra.com: How to Rationalize the Denominator
What do you do if the denominator contains a radical? This article explains how to rationalize a denominator that contains square roots, higher roots and the sums and differences of square roots. The examples also include problems that...
BBC
Bbc: Higher Bitesize Maths: Quadratic Theory
A tutorial on quadratics presents topics including: factoring and solving quadratics, graphing quadratic functions, using completing the square and the quadratic formula to solve functions, the discriminant and conjugates. Plenty of...
CK-12 Foundation
Ck 12: Algebra: Solving Quadratic Equations Study Guide
This comprehensive study guide highlights the main terms and formulas needed to review solving quadratic equations. Examples are included.