Sharp EL9900 manual Graphing Polynomials and Jumping to Find the Roots, = x 4 + x 3 5x 2 3x +

EL-9900 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

1-1Enter the polynomial

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

Y=	X/ /T/n		ab 4						+		X/ /T/n
						5				x2
ab 3				—				X/ /T/n
	3
—		X/ /T/n			+		1

1-2View the graph.

GRAPH

2-1Find the first root.

2nd F CALC

5

2-2Find the next root.

2nd F CALC 5

x -2.47

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

x -0.82

6-2