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The graph of y = ax^2 + bx + c, in which a, b, and c are real numbers, is shown.  What is the value of a + 2b - c?  Express your answer in simplest radical form.

 

 Jul 18, 2022
 #1
avatar+124524 
+1

In vertex form we have

 

y = a ( x -  h)^2  + k             (h,k)  is the vertex  and (x,y)  is a point on the graph

 

So

 

-8  = a( 0 - 1)^2  + (-9)

 

1  =  a1^2

 

a =  1 

 

So we have

 

y = ( x - 1)^2 - 9 

 

y  =x^2 - 2x + 1   - 9

 

y  = x^2  - 2x  -  8

 

b = -2       c =  -8

 

a + 2b  - c   =

 

1 + (2)(-2)  - (-8)  = 

 

1   - 4  +  8   =

 

5

 

 

cool cool cool

 Jul 18, 2022

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