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This may be somewhat of a basic question, but I need to know... I'm trying to find the minimum and maximum for the following: $y = \frac{\cos 3x}{5}+\sin 3x$

How is this done on a TI-83?

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    Thanks, Thomas, I figured out what was wrong: I had one of the plots under stat plots turned on so it wouldn't let me graph...2012-10-23

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  • You enter the function as (for example) a $Y_1$ (using the [y=] button).
  • You try to sketch the graph and adjust the window so that it shows the minimum or maximum that you want to find. (Hint: try for example $x_{min} = -5$, $x_{max} = 5$, $y_{min} = -2$, $y_{max} = 2$)

  • You click [2nd] [calc] and choose (say) minimum.

  • You put the cursor to the left of the minimum and click enter. You put it to the right and click enter.

  • You move the cursor so that it is close to where the minimum is and you click enter.

Note i your case, you will have infinitely many maximums and minimums since he function is periodic. When you find say a minimum, then you can add any (integer) multiple of $\frac{2\pi}{3}$ to get the other minimums. This should be clear from the graph.

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    You might try to reset the calculator. You can do this under the [mem] button.2012-10-23