Answers

2014-08-01T15:40:31+08:00
The vertex form of  x²-x-6    is      a(x-h)² + k
a=constant term,    h & k are the coordinates of the vertex
thus
x²-x-6 = (x²-x +1/4) - 6 - 1/4
           = (x-1/2)² - 25/4
so the coordinates of the vertex are      1/2, - 25/4

I just complete the square of ( x²-x ) by adding 1/4 and I minus back  1/4 to balance the equation
  
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