Checking Your Answer For A Composite Function; Turning Functions Off And On In The Graphing List - Texas Instruments TI-84 Plus Manual

To locate where
Press
[intersect].
jumps to the other function – here, the line. Next, press
to mark the second curve. Next, supply a guess for
ENTER
the point of intersection. Use
intersection point you want to find – in this case, the leftmost
point. Press
ENTER . The break even point occurs when 10,050
gallons are sold and revenue is $22,110.
CHECKING YOUR ANSWER FOR A COMPOSITE FUNCTION We illustrate this
technique with the functions that are given on page 16 of Section 1.1 of Calculus Concepts:
altitude = F(t) =
flight in minutes and air temperature = A(F) = 279(0.85
the number of thousand feet above sea level. Remember that when you enter functions in the
list, you must use
Y=
Press and clear each previously entered equation with
Y= ,
Enter F in
CLEAR .
+ 1 . 8 X,T,θ,n x
and enter A in
ENTER .
Enter the composite function (A
with the keystrokes
► 1 [Function] 1 [Y1] ) ENTER .
Next, enter your algebraic answer for the composite function in
. Be certain that you enclose the exponent in
Y4
tion in ) in parentheses.
Y1
(The composite function in the text is the one that appears to the
right, but you should enter the function that you have found for
the composite function.)
We now wish to check that the algebraic answer for the composite function is the same as the
calculator's composite function by evaluating both functions at several different input values.
You can do these evaluations on the home screen, but as seen below, using the table is more
convenient.
TURNING FUNCTIONS OFF AND ON IN THE GRAPHING LIST Note in the prior
illustration that we are interested in the output values for only
will list values for all functions that are turned on. (A function is turned on when the equals
sign in its location in the graphing list is darkened.) We now wish to turn off
16
, press
Y1 = Y2 2ND TRACE (CALC) 5
to mark the first curve. The cursor
ENTER
to move the cursor near the
◄
3 2
−
2t + 1.8t + 1.7t + 4.4 thousand feet above sea level where t is the time into
as the input variable.
X
by pressing
Y1
2
+ 1 . 7 X,T,θ,n +
by pressing
Y2 279 (
F)(x) = A(F(x)) =
o
VARS ► 1 [Function] 2 [Y2] ( VARS
F
) – 66 degrees Fahrenheit where F is
. 2 X,T,θ,n ^ 3
(−)
ENTER
4 4
.
. 85 ^ X,T,θ,n ) − 66
in
Y2(Y1) Y3
(the func-
Y4
Y3
Copyright © Houghton Mifflin Company. All rights reserved.
Chapter 1
and . However, the table
Y4
and .
Y1 Y2