Monday 4 June 2012

Deriving the Quadratic Formula

If you have studied Maths up to GCSE level then it is likely that you will have encountered a method of solving any quadratic equation (an equation of the form ax² + bx + c = 0) using the quadratic formula.



This formula is used to find where the quadratic equation crosses the x-axis (this is at y = 0). Although you have encountered this formula at GCSE it is unlikely that you will have encountered the proof as to why the formula works, which is a shame as it ties in some other GCSE Maths nicely and is in no way complex.

To solve ax² + bx + c = 0 for x you begin by completing the square, rearrange and find what x equals, simple!



And there it is, the quadratic formula! As you can see, it really isn't very difficult to derive the formula and it is a great shame that teachers do not take to the time to show students why the formula works rather than just letting them blindly accept it.

1 comment:

  1. All in all the children thoroughly enjoyed the trail. The only down side was that we ran out of time and weren't able to finish, but as each group had started in different places all the letters had been collected and someone was able to work out the word. Clearly if the trail is repeated, we will run it when there is more time available. help me with math

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