for all x, so there are not any critical points to this function.

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- June 16th 2013, 07:37 AM #1

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## mix/max problem

I am working on a mix/max problem and am stuck.

within the interval of [-1,4]. The exponent of e is , can't get Latex to cooperate with me.

Using the product rule to differentiate and I get:

y'=

Factor out the and I get

For all real numbers, the 2nd term will never equal 0, so the only one that can equal 0 is .

I don't know how to solve for x when . Any pointers?

- June 16th 2013, 07:41 AM #2

- June 16th 2013, 08:11 AM #3
## Re: mix/max problem

You missed a minus sign y'=

Look at this graph

About your LaTeX, If you have more than one character in an exponent the you must use {} around the entire exponent.

[TEX] e^{-\frac{x^2}{8}} [/TEX] gives .

- June 16th 2013, 08:30 AM #4

- June 16th 2013, 04:16 PM #5

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## Re: mix/max problem

Yup, I see my algebra error, it should be .

I also screwed up the interval. It should be [-4,1].

The derivative is

Some factoring and I get

The e term can't be 0 for all of x (although my TI-84 gives an error when x=-100, not sure why), and the only number that makes the 2nd term zero is either -2 or 2. Only -2 is in the interval, so I need to find out f(x).for x= -4, -2, and 1. Biggest number is max, smallest is min. I might just understand this yet.

I appreciate the help.