Question 807278: so the question says "suppose you are told that a parabola goes through the points (-7,11) and (3,11). What is th x-coordinate of the vertex? how do you know?"
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website! a parabola goes through the points (-7,11) and (3,11). What is th x-coordinate of the vertex?
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Vertex form of equation for a parabola:  , (h,k)=(x,y) coordinates of the vertex.
Assuming A=1
y=(x-h)^2+k
plug in given points,(-7,11) and (3,11), on given parabola for 2 equations:
..
11=(-7-h)^2+k
11=(3-h)^2+k
subtract
0=49+14h+h^2-9+6h-h^2
20h+40=0
20h=-40
h=-2
..
k=11-(3-h)^2
k=11-5^2=11-25=-14
..
x-coordinate of vertex=-2
y-coordinate of vertex=-14
Equation: 
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