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A quadratic of the form \(-2x^2 + bx + c\) has roots of x = 3 + sqrt5 and x = 3 - sqrt{5} The graph of y = -2x^2 + bx + c is a parabola. Find the vertex of this parabola.

I think I might know how to start this, but any hints appreciated!

 Oct 6, 2020
 #1
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This equals   (x-3-sqrt5)(x-3+sqrt5)             

  c would equal the red parts multiplied together and then multiplied by -2 ( because the x^2 has a -2 coefficient)

  b would equal the red parts added together and multiplied by -2

 

Vertex 'x' value is then =  -b/2a      get the y value of the vertex by putting 'x' into the equation and calculating....

 Oct 6, 2020
 #2
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tysm for the hints! i get it now :)

violetzhang07  Oct 6, 2020

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