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The graph of a certain quadratic y=ax^2+bx+c is a parabola with vertex (-4,0) which passes through the point \((1,-7)\). What is the value of a?

 Apr 24, 2022
 #1
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(-4,0)  is a root  ....so.....

 

If we  shifted  this   parabola to  the right by 4 units  the vertex is (0,0) and  we  would get rid of the  bx  and c   terms   

 

And now..... ( 1 + 4, -7)  becomes (5 , -7)  

 

So

 

y=  ax^2

 

-7 =  a (5)^2

 

-7 = 25a

 

a = -7  / 25

 

 

cool cool cool

 Apr 24, 2022
edited by CPhill  Apr 24, 2022

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