Sunday, November 11, 2012

How do you solve a quadratic by completing the square?

                Ahh quadratics! They suck and we all hate them but, we still have to solve them. Instead of suffering through that long quadratic formula way of solving them I present you with an easier, simpler, and faster way of solving most quadratic equations. This method would be solving quadratics by completing the square. Now you start off with a simple quadratic such as: 
                                                         4x2 – 2x – 5 = 0
           Now instinct would tell you oh plug it all in but no. Instead you add 5 to the other side of the equation. I know this is completely different then what you're used to, but trust me on this. After adding five you're left with 
                                                              4x2 – 2x = 5
                  Now there are a few steps you have to do now. First you have to get rid of the four so that there is no coefficient in front of the squared term. Now after that you divide the second term by 2 and then square it. Whatever you get you add it to both sides.That was a lot of information, but this is how you do it.  
               
                                          
                 See not that hard? Now you have completed the square but your answer isn't finished. Now you take the square root of both sides of the equation.
                           
                                           
                   You're almost done now! All that;s left is solving for X. The change to the plus or minus symbol signifies that you will have two answers. Remember quadratics are square because you have two answers. 
                                                       
                  You're final answer looks something like:
  
                                           
                   See not so bad huh? It takes some getting used to but once you master these steps you'll be solving quadratics by completing the square all the time. Unless of course you love that quadratic formula.

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