SOLUTION: Without graphing, determine whether the following paraholas opens upward or downward and find the vertex.
I know it opens downward and the vertex is (-1,8) I just don't know how
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Question 328147: Without graphing, determine whether the following paraholas opens upward or downward and find the vertex.
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
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
You didn't bother to share the function, but there are a few things that I can share that might help anyway.
For any quadratic polynomial function of the form:
\ =\ ax^2\ +\ bx +\ c)
If 
the graph opens upward, that is, the vertex is a minimum. If 
the graph opens downward.
The 
-coordinate of the vertex is given by 
, and the 
-coordinate of the vertex is given by \ =\ a\left(\frac{-b}{2a}\right)^2\ +\ b\left(\frac{-b}{2a}\right)\ +\ c)
So from what you have told me:
The -coordinate of the vertex is:
The -coordinate of the vertex is:
\ =\ a(-1)^2\ +\ b(-1) +\ c\ =\ 8)
John
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