Sharp EL9900 manual 2nd F Calc 2 x = = 9.999999999 Note

EL-9900 Graphing Calculator

Step & Key Operation Display Notes

2-1Enter the function y =3.5x + 4for Y1. Enter y = 10 for Y2.

Y= CL MATH B 1

3 • 5 X//T/n + 4 ENTER

1 0

2-2Set up shading.

2nd F DRAW G 1

2nd F VARS A ENTER A 2

2nd F VARS ENTER 1

Since the inequality you are solving is Y1 > Y2, the solu- tion is where the graph of Y2 is “on the bottom” and Y1 in “on the top.”

2-3Set viewing window to “-10 < x < 10” and “-5 < y < 50”, and view the graph.

WINDOW (-) 1 0 ENTER 1 0

ENTER ENTER (-) 5 ENTER 5 0

ENTER 5 ENTER

2-4Find the points of intersection. Solve the inequality.

2nd F CALC 2 ➞ x = -4,y = 10

2nd F CALC 2 ➞ x = 1.714285714

y = 9.999999999 ( Note)

The intersections are (-4, 10) and (1.7, 10.0). The solution is all values of x such that

x <- 4 or x >1.7.

( Note: The value of y in the intersection of the two graphs may not appear exactly as 10 as shown in the example, due to an error caused by approxi- mate calculation.)

The EL-9900 shows absolute values with , just as written on paper, by using the Equation editor. Graphical solution methods not only offer instructive visualization of the solution process, but they can be applied to inequalities that are often difficult to solve algebraically. The Shade feature is useful to solve the inequality visually and the points of intersection can be obtained easily.

10-3