Casio fx-9860GII - 1.15 Evaluating logarithms

Using a graphic display calculator
© Oxford University Press 2012: this may be reproduced for class use solely for the purchaser’s institute
Casio fx-9860GII
Press
OPTN
F2
GLINK.
As the value of x gets smaller, Y
1
gets closer and closer to 2.
Press
EXIT
and then press
F5
SET.
Change the minimum value of x to –12.
EXE
F6
F5
G·CON
OPTN
F2
GLINK.
Eventually the value of Y
1
displayed in the table reaches 2.
You can see, at the bottom of the screen, that the actual value of Y
1
is
2.000001882...
We can say that Y
1
→ 2 as x → − ∞ .
The line x = 2 is a horizontal asymptote to the curve y = 3
x
+ 2.
Logarithmic functions
1.15 Evaluating logarithms
Example 18
Evaluate log
10
3.95, ln 10.2 and log
5
2.
Press
MENU
. You will see the dialog box as shown on the right.
Choose 1: RUN·MAT and press
EXE
.
Press
EXIT
until you see the menu on the right, then press
F4
MATH.
Press
F2
logab to open the logarithm template.
For natural logarithms it is possible to use the same method, with the base
equal to e, but it is quicker to press
ln
. Similarly for logarithms to base
10 you can press
log
.
Note that the GDC will evaluate logarithms with any base without having
to use the change of base formula.
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