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Zeros of Functions


 

The graphing calculator is very helpful when determining the zeros of functions (the locations were the graph crosses the x-axis --- the roots).


       Using the ZERO command:
Solve: 

Since this equation is set equal to zero, the zeros (roots) will be the locations where the graph crosses the x-axis (if the roots are real numbers).
1.  Set
2.  Use the ZERO command to find the zeros (roots) --  2nd TRACE (CALC), #2 zero
3.  Left bound?  Move the spider as close to the zero (root --- where the graph crosses the x-axis) as possible.  Hit the left arrow to move to the "left" of the zero (root).  Hit ENTER.  A "marker" will be set to the left of the zero (root).
4.  Right bound?  Move the spider as close to the zero (root --- where the graph crosses the x-axis) as possible.  Hit the right arrow to move to the "right" of the zero (root).  Hit ENTER.  A "marker" will be set to the right of the zero (root).
5.  Guess?  Just hit ENTER.
6.  Repeat the entire process to find other zeros (roots --- which in this case the second root happens to be x = 7).

Answer:  one of the zeros (roots) is x = -2

 

Standard 10 x 10 window


 


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