SITE-A teams: Lesson 21

 

Solving an equation of quadratic form can be accomplished graphically using the CASIO fx7400G.

Solve for x: x4 - 13 x2 + 36 = 0

Turn on the CASIO fx7400G.

Ac_on.gif (1767 bytes)

Use your cursor arrows to highlight the GRAPH menu and press exe.gif (1747 bytes) or just press 4.gif (1703 bytes) when at the main menu screen.

In the Y1 slot enter the expression X4 - 13 X2 + 36 and press exe.gif (1747 bytes)

(Make sure no other Y-slot is highlighted, i.e. selected for graphing.)

Press shiftf3.gif (1888 bytes) (V-Window)

Set up the viewing window as follows:

Xmin    -3.9    Ymin:     -23

max:      3.9    max:      23

s c l:        1      s c l:    5

Press quit.gif (1764 bytes)

Press f4.gif (1732 bytes) (DRAW)

The graph appears on the screen of the calculator. Press shiftf1.gif (1869 bytes) (Trace) and use the right cursor arrow to move the "cross hairs" to where the graph crosses the x-axis. This is at the points ( -3, 0 ), ( -2, 0 ), ( 2, 0 ), and ( 3, 0 ). Thus the real-valued solutions are: x = -3, x = - 2, x = 2, and x = 3.

Press quit.gif (1764 bytes)

Highlight the expression and de-select it by pressing f1.gif (1719 bytes) (SEL) or delete it by pressing f2.gif (1726 bytes) (DEL)

Solve for x: x6 + 7 x3 - 8 = 0

In the Y2 slot enter the expression X6 + 7 X3 - 8 and press exe.gif (1747 bytes)

(Make sure no other Y-slot is highlighted, i.e. selected for graphing.)

Press f4.gif (1732 bytes) (DRAW)

The graph appears on the screen of the calculator. Press shiftf1.gif (1869 bytes) (Trace) and use the right cursor arrow to move the "cross hairs" to where the graph crosses the x-axis. This is at ( -2, 0 ) and ( 1, 0). Thus the real-valued solutions are: x = -2 and x = 1.

 

Press quit.gif (1764 bytes)

Highlight the expression and de-select it by pressing f1.gif (1719 bytes) (SEL)

or delete it by pressing f2.gif (1726 bytes) (DEL)

Solve for x: lesson21.gif (1848 bytes)

In the Y3 slot enter the expression 2 X + 3 Ö X - 2 and press exe.gif (1747 bytes)

(Make sure no other Y-slot is highlighted, i.e. selected for graphing.)

Press f3.gif (1726 bytes) (V-Window)

Set up the viewing window as follows:

Xmin: -1.95    Ymin: -1.15

max:    1.95     max:      1.15

s c l:     0.5     s c l:      0.5

Press quit.gif (1764 bytes)

Press f4.gif (1732 bytes) (DRAW )

The graph appears on the screen of the calculator. Press shiftf1.gif (1869 bytes) (Trace) and use the right cursor arrow to move the "cross hairs" to where the graph crosses the x-axis. This is at x = 0.25 and y = 0. Thus the real-valued solution is x = 0.25.

Press quit.gif (1764 bytes)

Highlight the expression and de-select it by pressing f1.gif (1719 bytes) (SEL) or delete it by pressing f2.gif (1726 bytes) (DEL)

Press menu.gif (1772 bytes)

Turn off the CASIO fx7400G. Press shiftac.gif (1924 bytes) (OFF)