3 constructed functions – Texas Instruments TI-85 User Manual
Page 16
B-16
TI-85/TI-86 Graphing Calculators
Copyright © Houghton Mifflin Company. All rights reserved.
To graphically find an x-intercept, i.e., a value of x at
which the graph crosses the horizontal axis, first press
EXIT
to return the menu to the bottom of the screen.
TI-85
Press
F1
(
MATH
)
F3
(
ROOT
)
TI-86
Press
F1
(
MATH
)
F1
(
ROOT
)
Both
Use
to move the trace cursor near the first
x-intercept, and press
ENTER
.
To find the second x-intercept, press
EXIT
and the
F
-key under
ROOT
, use
to move the trace cursor
near the other x-intercept, and press
ENTER
.
&
1.3 Constructed Functions
Your calculator can find output values of and graph combinations of functions in the same
way that you do these things for a single function. The only additional information you need
is how to enter constructed functions in the graphing list. Suppose that a function f(x) has
been entered in
y
1
and a function g(x) has been entered in
y
2
.
¥ Enter
y
1
+
y
2
in
y
3
to obtain the sum function (f+g)(x) = f(x) + g(x).
¥ Enter
y
1
Ð
y
2
in
y
4
to obtain the sum function (fÐg)(x) = f(x) Ðg(x).
¥ Enter
y
1
*
y
2
in
y
5
to obtain the product function (f.g)(x) = f(x) * g(x).
¥ Enter
y
1
/
y
2
in
y
6
to obtain the quotient function (f
¸g)(x) =
f x
g x
( )
( )
.