Finding An Inverse Function - Casio fx-9860GII Instructions Manual

1.16 Finding an inverse function

The inverse of a function can be found by interchanging the x and y values.
Geometrically this can be done by refl ecting points in the line y = x.
Example 19
Show that the inverse of the function y = 10
Press MENU . You will see the dialog box as shown on the right.
Draw the line y = x so that it can be recognised as the axis of refl ection.
Choose 5: GRAPH and press
EXE
Type x and press .
EXE
Type 10 x and press
SHIF T F3
Press V-Window and choose
axes which are −6.3 ≤ x ≤ 6.3 and −3.1 ≤ y ≤ 3.1.
EXE F6
Press and DRAW.
The graphs of y = x and y = 10
F4
Press SHIF T Sketch |
Press to select the curve Y2 = 10
EXE
Press .
The calculator will display the inverse of the function y = 10
Press EXIT to display the Y= editor.
Type log (x).
EXE
Press and F6 DRAW to display the graphs of y = x,
y = 10 x and y = log x.
10
The inverse function and the logarithmic function coincide, showing
that y = log x is the inverse of the function y = 10
10
© Oxford University Press 2012: this may be reproduced for class use solely for the purchaser's institute
x
is y = log
EXE
.
X,i,T
Use to
.
enter x.
F1
INIT to set up square
x
are displayed.
F4 Inv.
x
.
Press
log(x).
to enter log
x by refl ecting y = 10
10
1 0
Note: Type 10
x
X,i,T
10
to enter .
x
.
log X,i,T
to enter
log
is a shorter way
.
10
x .
Casio fx-9860GII
x
in the line y = x.
Using a graphic display calculator 21