Texas Instruments TI-82 Manual page 18

A-18
TI-82/TI-83 Graphics Calculators
The value of the leftmost x-intercept is displayed as
X = 0.58578644.
Repeat the above procedure to find the other x-intercept.
Confirm that it is X = 3.4142136.
&
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
¥ Enter Y + Y
1 2
¥ Enter Y Ð Y
1 2
¥ Enter Y *Y in Y
1 2
¥ Enter Y /Y in Y
1 2
¥ Enter Y (Y ) in Y
1 2
Your calculator will evaluate and graph these constructed functions. Although it will not
give you an algebraic formula for a constructed function, you can check your algebra by
evaluating the calculator-constructed function and your constructed function at several
different points.
1.3.1 GRAPHING PIECEWISE CONTINUOUS FUNCTIONS
functions are used throughout the text. It is often helpful to use your calculator to graph and
evaluate outputs of piecewise continuous functions. Consider the following example.
The population of West Virginia from 1985 through 1993 can be modeled by
ì
=
P t ( ) í
î
where t is the number of years since 1900.
TI-82 Enter the function P(t), using x as the input variable,
in the Y location of the Y= list using the keystrokes
1
23.514
(–)
( )
MATH TEST
972.6 ) (
and a function g(x) has been entered in Y
1
in Y to obtain the sum function (f+g)(x) = f(x) + g(x).
3
in Y to obtain the sum function (fÐg)(x) = f(x) Ðg(x).
4
to obtain the product function (f . g)(x) = f(x) * g(x).
5
to obtain the quotient function (f ¸ g)(x) =
6
to obtain the composite function (f
7
- +
23 514 . t 3903 667 . thousand people when
+
9 1 . t 972 6 . thousand people when
q
+
X,T,
3903.667
+
(<) 90 )
5
q
X,T, (
2nd MATH
.
2
f x
g x
g)(x) = f(g(x)).
o
85
£ £
90 t 93
(
q
X,T,
) (
2nd
q
+
X,T,
( 9.1
) (³) 90 )
TEST 4
Copyright © Houghton Mifflin Company. All rights reserved.
( )
.
( )
Piecewise continuous
£ <
t 90