SOLUTION: Without graphing, determine whether the following paraholas opens upward or downward and find the vertex. g(x)=-4(x+1)^2+8 I know it opens downward and the vertex is (-1,

Algebra ->  Linear-equations -> SOLUTION: Without graphing, determine whether the following paraholas opens upward or downward and find the vertex. g(x)=-4(x+1)^2+8 I know it opens downward and the vertex is (-1,      Log On


   

Question 328402: Without graphing, determine whether the following paraholas opens upward or
downward and find the vertex.
g(x)=-4(x+1)^2+8

I know it opens downward and the vertex is (-1,8) I just don't know how it was
found. Can you please help.

Thanks
Found 2 solutions by Alan3354, Fombitz:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Without graphing, determine whether the following paraholas opens upward or
downward and find the vertex.
g(x)=-4(x+1)^2+8
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The 1st term is -4x^2, so it opens downward (the negative sign --> downward)
g(x)=-4(x+1)^2+8
The vertex is on the line of symmetry, x = -1
g(-1) = 8
Vertex = (-1,8)
------------
I swear I didn't graph it.

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
DUPLICATE
Previously answered See Answer 235190.

It opens downward because the x%5E2 coefficient is negative (-4).
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It's in vertex form y=a%28x-h%29%5E2%2Bk where (h,k) is the vertex.
If the parabola opens upwards, the vertex y coordinate is the minimum y value.
If the parabola opens downwards, the vertex y coordinate is the maximum y value.
In this case, ymax=8
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