Solving equations with light. (Courtesy: iStockphoto/Henrik Jonsson) 3x + y = 2. x + 3y = 0. It’s the sort of easy maths problem that you can work out in a few minutes using pencil and paper, but ...

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Do this, and you’ll get the quadratic formula. (See the exercises below for more details.) This isn’t as easy as humming a children’s tune, but it demonstrates the important algebraic and geometric ...

Many former algebra students have painful memories of struggling to memorize the quadratic formula. A new way to derive it, overlooked for 4,000 years, is so simple it eliminates the need.