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Casio TEAMS Grant Algebra Lessons XXI
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.

Use your cursor arrows to highlight the GRAPH menu and press
or just press
when at the main menu screen.
In the Y1 slot enter the expression X4 - 13 X2 + 36 and
press 
(Make sure no other Y-slot is highlighted, i.e. selected for graphing.)
Press
(V-Window)
Set up the viewing window as follows:
Xmin: -3.9 Ymin: -23 max : 3.9 max : 23 scl : 1 scl : 5
Press 
Press (DRAW)
The graph appears on the screen of the calculator. Press
(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
Highlight the expression and de-select it by pressing
(SEL) or delete it by pressing
(DEL)
Solve for x: x6 + 7 x3 - 8 = 0
In the Y2 slot enter the expression X6 + 7 X3 - 8 and
press 
(Make sure no other Y-slot is highlighted, i.e. selected for graphing.)
Press
(DRAW)
The graph appears on the screen of the calculator (See graph below). Press
(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 
Highlight the expression and de-select it by pressing
(SEL) or delete it by pressing
(DEL)
Solve for x: 
In the Y3 slot enter the expression 2 X + 3 ª X - 2 and press 
(Make sure no other Y-slot is highlighted, i.e. selected for graphing.)
Press
(V-Window)
Set up the viewing window as follows:
Xmin: -1.95 Ymin: -1.15 max : 1.95 max : 1.15 scl : 0.5 scl : 0.5
Press 
Press
(DRAW )
The graph appears on the screen of the calculator. Press
(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.
Highlight the expression and de-select it by pressing
(SEL) or delete it by pressing
(DEL)
Press 
Turn off the CASIO FX7400G.
(OFF)
Graph of y =

Graph of y =

Graph of y = - x3 - x2 + 4 x + 4

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