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QUESTION

Find and classify the stationary point of the function
$f(x)=1+2x-x^2$.

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ANSWER

$\ds f(x)=1+2x-x^2,\ \frac{df}{dx}=2-2x=0$ for a stationary point
therefore $\ds x=1.\ \frac{d^2f}{dx^2}=-2<0$ therefore $x=1$ is a
maximum.




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