Let ${\displaystyle \underset{0}{\overset{2}{}}}f(x)dx=8$

What is the average value of $f(x)$ on the interval from $x=0$ to $x=2?$

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If $f(x)$ is even, what is ${\displaystyle \underset{-2}{\overset{2}{}}}f(x)dx?$

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If $f(x)$ is even, what is the average value of $f(x)$ on the interval $x=-2$ to $x=2?$

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