Operation Manual

Chapter 6: Sequence Graphing 107
Defining and Displaying Sequence Graphs
Graphing Mode Similarities
The steps for defining a sequence graph are similar to the steps for defining a function graph.
Chapter 6 assumes that you are familiar with Chapter 3: Function Graphing. Chapter 6 details aspects of
sequence graphing that differ from function graphing.
Setting Sequence Graphing Mode
To display the mode screen, press z. To graph sequence functions, you must select Seq graphing
mode before you enter window variables and before you enter sequence functions.
Sequence graphs automatically plot in Simul mode, regardless of the current plotting-order mode
setting.
Sequence Functions u, v, and w
The TI-84 Plus C has three sequence functions that you can enter from the keyboard: u, v, and w. They
are second functions of the ¬, −, and ® keys. Press y [u] to enter
u, for example.
The Sequence functions u, v and w can also be entered using the
Y-VA RS shortcut menu t a.
You can define sequence functions in terms of:
• The independent variable
n
• The previous term in the sequence function, such as u(nN1)
• The term that precedes the previous term in the sequence function, such as u(nN2)
• The previous term or the term that precedes the previous term in another sequence function, such
as
u(nN1) or u(nN2) referenced in the sequence v(n).
Note: Statements in this chapter about
u(n) are also true for v(n) and w(n); statements about u(nN1)
are also true for
v(nN1) and w(nN1); statements about u(nN2) are also true for v(nN2) and w(nN2).
Displaying the Sequence Y= Editor
After selecting Seq mode, press o to display the sequence Y= editor.
5. Press p 0 to set nMin=0. Press † 50 to set
nMax=50. nMin and nMax evaluate forest size over
50 years. Set the other window variables.
PlotStart=1 Xmin=0 Ymin=0
PlotStep=1 Xmax=50 Ymax=6000
Xscl=10 Yscl=1000
6. Press r. Tracing begins at nMin (the start of the
forestry plan). Press ~ to trace the sequence year by
year. The sequence is displayed at the top of the
screen. The values for
n (number of years), X (X=n,
because
n is plotted on the x-axis), and Y (tree count)
are displayed at the bottom. When will the forest
stabilize? With how many trees?