SOLUTION: what is the quadratic formula? what is the origin of the quadratic formula?

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Question 391285: what is the quadratic formula?
what is the origin of the quadratic formula?

Found 2 solutions by richard1234, solver91311:
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
The quadratic formula says that the two roots of any second degree polynomial {{ax^2 + bx + c}}} are x+=+%28-b+%2B-+sqrt%28b%5E2+-+4ac%29%29%2F2a.

It is possible to derive the quadratic formula by completing the square. This Wikipedia article lists multiple ways to derive the formula:

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

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


The quadratic formula gives the general solution of a quadratic equation. The formula was developed by completeing the square on the general quadratic equation:



Move the constant term to the RHS:



Divide by the lead coefficient:



Divide the coefficient on the 1st degree term by 2, square the result, then add that result to both sides of the equation:



Apply the LCD and complete the sum in the RHS:



Factor the perfect square in the LHS:



Take the square root remembering to consider both the positive and negative root:



Add to both sides:



John

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