Beginning Skills:  Zoom menu

The center key in the top row is the Zoom menu key.   Pressing it shows this screen:
         and scrolled down to see the rest   :                                   
This course uses the following options. We will NOT use options 7 or 8. 
Click to see how to use each option..

Selecting the first option, ZBOX, allows the user to enlarge the graph within a specific rectangle.

a) Here is a graph in the standard screen:  Pressing the TRACE key shows the equation and the coordinates.






b)  When ZBOX is selected a blinking "+" will show in the graph screen. Move it with the arrow keys so a corner of the box you will make is where you wish it to be,  then press ENTER. 
c) Use the arrow keys to trace out the box with the desired graph inside it. After using the down arrow:





 
                after using the right arrow:




   
d)  When the box is complete, Press ENTER.
      Now the intercept can be seen with more accuracy.  This skill is very handy when analyzing graphs for roots of equations.
                                                         

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   ZOOM-IN does just that.  Select it, move the "+" to the center of the section you want to see close up, and press ENTER. (OR press ZOOM and 1) The window automatically resets with that point in the center of the screen.  This process can be repeated over and over.


   Press ZOOM-IN once to get:


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  ZOOM-OUT does the opposite of Zoom IN and works exactly the same way.  This is handy if a key point in your graph is not visible because the window is too small.  It is sometimes not so great if you find you really only wanted to change the scale of one axis and not both.
  ZOOM-OUT once to get:        

This cubic graph is incomplete.  First choose ZOOM-OUT, then choose the center of the zoomed in graph.   Here is a good choice:    so the new view looks like this:  Now all key points can be seen.
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ZSQUARE adjusts the screen to make the slope of a striaght line and circles closer to scale.  The normal screen has pixels, ie, graph grid squares, that are not square.  ZSQUARE fixes that.

Here are a circle and line of slope 2 on the standard screen:

And now after pressing ZOOM-5:

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  ZSTANDARD   is the most-used option.   Whenever you want to graph an equation, and you are not sure what values are set in the window, press ZOOM-6 and the equation will graph in the standard window, which is -10 to +10 in both x and y axes.

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ZoomStat  is a more advanced option and will be taken up in another section.

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  ZoomFit can be a helpful tool to find a good window. This routine takes whatever DOMAIN values (horizontal axis) and adjusts the RANGE values so the graph is on screen throughout the interval.  It is a bit tricky to use, as the Domain must be just right to get a good result.  Sometimes even then, manipulating the Domain and Range in the WINDOW screen is a better option.

Here is an example: standard screen:
This cubic equation graph has a relative minimum that is off the screen.

And here is the ZOOM-0 screen:
Now the minimum is seen.

Remember, this is a tricky function.  The new graph will use whatever x-axis boundaries are set.  If you don't like what you see, try changing the x-values in the window.

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