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EL-9900 Graphing Calculator
Graphing Polynomials and Tracing to Find the Roots
A polynomial y = f (x) is an expression of the sums of several terms that contain different
powers of the same originals. The roots are found at the intersection of the x-axis and
the graph, i. e. when y = 0.
Draw a graph of a polynomial and approximate the roots by using the Zoom-in and
Trace features.
1. Graph the polynomial y = x
3
- 3x
2
+ x + 1.
2. Approximate the left-hand root.
3. Approximate the middle root.
4. Approximate the right-hand root.
Enter the polynomial
y = x
3
- 3x
2
+ x + 1.
1-1
Example
6-1
Notes
Step & Key Operation
Display
There may be differences in the results of calculations and graph plotting depending on the setting.
Return all settings to the default value and delete all data.
Set the zoom to the decimal window:
( )
Setting the zoom factors to 5 :
A
ZOOM
ZOOM
B
7
55
2nd F
QUIT
ENTER
ENTER ENTER
ENTER
ALPHA
Before
Starting
1
3
—
X/
/T/n
3
+
X/
/T/n
Y=
X/
/T/n
a
b
+
1-2
View the graph.
GRAPH
x
2