Sharp EL-9400, EL-9600c Graphing Polynomials and Jumping to Find the Roots, 1-1 1-2 2-1, Example

EL-9650/9600c/9450/9400 Graphing Calculator

Graphing Polynomials and Jumping 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.

Example

Draw a graph of a polynomial and find the roots by using the Calculate feature. 1. Graph the polynomial y = x 4 + x 3 - 5x 2 - 3x + 1.

2. Find the four roots one by one.

Before There may be differences in the results of calculations and graph plotting depending on the setting. Starting Return all settings to the default value and delete all data.

Setting the zoom factors to 5 : ZOOM A * ENTER A ENTER A ENTER 2nd F QUIT

Step & Key Operation	Display	Notes
(When using EL-9650/9600c)	(When using EL-9650/9600c)
*Use either pen touch or cursor to operate.

1-1

1-2

2-1

Enter the polynomial

y = x 4 + x 3 - 5x 2 - 3x + 1

									+
Y=	X/ /T/n ab 4							*
ab 3			*	—	5		X/ /T/n
	3
—		X/ /T/n		+		1

View the graph.

GRAPH

Find the first root.

2nd F CALC

5*

X//T/n

x 2

x -2.47

Y is almost but not exactly zero. Notice that the root found here is an approximate value.

2-2Find the next root. x -0.82

2nd F CALC 5 *

4-2