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 Post to:   Explanation:

In mathematics, a quadratic equation is a polynomial equation of the second degree. The general form is where x represents a variable, and a, b, and c, constants, with a ≠ 0. (If a = 0, the equation becomes a linear equation.)

The constants a, b, and c, are called respectively, the quadratic coefficient, the linear coefficient and the constant term or free term. The term "quadratic" comes from quadratus, which is the Latin word for "square". Quadratic equations can be solved by factoring, completing the square, graphing, Newton's method, and using the quadratic formula

In elementary algebra, completing the square is a technique for converting a quadratic polynomial of the form to the form In this context, "constant" means not depending on x. The expression inside the parenthesis is of the form (x − constant). Thus one converts ax2 + b x + c to and one must find h and k.

Completing the square is used in solving quadratic equations.

### General description

Given any quadratic of the form it is possible to form a square that has the same first two terms: This square differs from the original quadratic only in the value of the constant term. Therefore, we can write where k is a constant. This operation is known as completing the square. For example: For an equation involving a non-monic quadratic, the first step to solving them is to divide through by the coefficient of x2. For example: (Our solved example in mathguru.com uses this concept).

http://en.wikipedia.org/wiki/Completing_the_square