SOLUTION: f(x)=x2 + 2x - 9 determine whether the given quadratic function has a minmum or maximun value. then find the coordinated of the mininmun or maximun point.

Algebra ->  Algebra  -> Quadratic Equations and Parabolas -> SOLUTION: f(x)=x2 + 2x - 9 determine whether the given quadratic function has a minmum or maximun value. then find the coordinated of the mininmun or maximun point.      Log On

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Question 636499: f(x)=x2 + 2x - 9
determine whether the given quadratic function has a minmum or maximun value. then find the coordinated of the mininmun or maximun point.
Answer by josmiceli(9671) About Me  (Show Source):
You can put this solution on YOUR website!
+f%28x%29+=+x%5E2+%2B+2x+-+9+
Since the coefficient of the squared term is positive
( +1 ), then the function has a minimum.
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The +x+ value of the minimum will
be at +-b+%2F+%282a%29+ when the
equation is in the form +f%28x%29+=+a%2Ax%5E2+%2B+b%2Ax+%2B+c+
+-b%2F%282a%29+=+-2+%2F+%282%2A1%29+
+-2+%2F+%282%2A1%29+=+-1+
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Plug this back into the equation
+f%281%29+=+%28-1%29%5E2+%2B+2%2A%28-1%29+-+9+
+f%281%29+=+1+-+2+-+9+
+f%281%29+=+-10+
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So the minimum is at (-1,-10)
Here's a plot:
+graph%28+400%2C+400%2C+-10%2C+10%2C+-20%2C+10%2C+x%5E2+%2B+2x+-+9%29+