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Help! 

3x2-5x+1=0

AND

2x2-7x+12=0

 Feb 3, 2020
 #1
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to complete the square, the leading coefficient has to be '1'

3x^2  - 5x   + 1 = 0      leading coefficient is '3'     divide the whole equation by 3

  x^2  - 5/3 + 1/3  = 0       now leading coefficient is 1 

                                              now take 1/2 of the MIDDLE coefficient (-5/3      one half is  -5/6)    then square it and add it to BOTH sides of the equation:     x^2 - 5/3   + 1/3    +    25/36   = 25/36    now you can do this:

                    (x- 5/6)^2     + 1/3    =  25/36             ( note how the green 25/36 is 'built in' to the (x-5/6)^2 component)

                                now   subtract   1/3   from both sides to clean it up a bit

                     (x-5/6)^2   =   25/36 - 12/36

                     (x-5/6)^2 = 13/36                           done.    You try the second one.......cheeky

 Feb 3, 2020

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