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October 28th, 2007, 06:51 PM   #1
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extreme values

Find the extreme values for this function: y=2x^2-8x+9. I got 2, so that y=1, but the books says '1' is the absolute minimum, but I think it should be local minimum because it didn't tell us the domain. Hope you can help, thanks.
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October 28th, 2007, 09:23 PM   #2
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the reason why it's an absolute minimum is because this is a parabola with a positive coefficient of the x^2 term. the point (2,1) is the vertex of the parabola.
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October 28th, 2007, 11:09 PM   #3
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If the domain is a real interval (such as all reals) that includes x = 2, the point (2, 1) is a local minimum and the absolute minimum.
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October 29th, 2007, 03:21 PM   #4
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Quote:
Originally Posted by jjinking
the reason why it's an absolute minimum is because this is a parabola with a positive coefficient of the x^2 term. the point (2,1) is the vertex of the parabola.
How do you find the vertex?
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October 29th, 2007, 05:15 PM   #5
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y = 2(x − 2)² + 1
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