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I'm stuck on this problem involving open intervals and absolute maximum/minimum.

$$H(t)=t^6-\frac{3}{4}t^8$$ On what intervals is the function increasing? Decreasing? What are the absolute maximum? Minimum?

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    I see that you have to use test points, but I don't understand the process2012-11-12
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    Note that because $H(t)$ only involves even powers of $t$, we have $H(t)=H(-t)$. So our curve is **symmetrical** about the $y$-axis. That will help as a check on the correctness of your calculations. For example, the function is decreasing on $[1,\infty)$, so it must be increasing on $(-\infty,-1]$.2012-11-12
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    Here is a [related problem](http://math.stackexchange.com/questions/173604/monotonocity-of-the-function/173622#173622).2012-11-12

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