SOLUTION: The function f(x)=x^2-9x+14 has a maximum or minimum value? What is the value?

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Question 1033705: The function f(x)=x^2-9x+14 has a maximum or minimum value? What is the value?
Found 3 solutions by josgarithmetic, josmiceli, ikleyn:
Answer by josgarithmetic(39617)   (Show Source): You can put this solution on YOUR website!
Based on so vertex minimum. The vertex occurs in the exact middle of the x-axis intercepts, but does not occur on the axis.

Try finding the vertex putting function into standard form.



This general form indicates that vertex is ( -b/2, c-b^2/4 );


This is .

Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!

The vertex ( either maximum or minimum )
is at when the form is:





------------------------
Another way to see this is: the vertex is midway
between the roots




-------------
The midway point is at:


---------------------
Plug this value back into equation




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The vertex is at ( 9/2, -25/4 ), which means it must be
a minimum since there are 2 roots on either side which
are above the vertex.
--------------------
Here's the plot:

Answer by ikleyn(52786)   (Show Source): You can put this solution on YOUR website!
.
This quadratic function has the coefficient 1 at .
Hence, the parabola is open upward.


Memorize it:

   If the coefficient at  is a positive number, then 
   the quadratic function is a parabola open upward and has a minimum.


   If, in opposite, the coefficient at  is a negative number, then 
   the quadratic function is a parabola open downward and has a maximum.


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