Texas Instruments TI-92 Getting Started page 26

5.5.4 Exponential Growth Model: The table shows the world population (in millions) from 1980 to 1992.
Year 1980
Population 4453
(millions)
Clear the previous data by going to the current variable in the Data/Matrix Editor and pressing F1 [Tools] 8[Clear
Editor] ENTER. Follow the procedure described above to enter the data in order to find an exponential model that
approximates the given data. Use 0 for 1980, 5 for 1985, and so on.
The TI-92 will not compute the exponential growth model y = ae
compute is of the form y = ab
to 4[ExpReg], the x variable to c1, and the y variable to c2. Then press ENTER to find the values of a and b
(Figure 5.73). In this case, the exponential growth model is y = 4451(1.017454
cx
ae , the required equation is c = ln b, and the exponential growth model in this case is y = 4451e
0.017303t
4451e .
If you wish to plot and graph the data, follow the method for linear regression. Set an appropriate range for the data
and then press GRAPH. The data will now be plotted in the range. To graph the regression equation also, store
the regression equation to a y plot that is free. As in the linear regression model, press
any other existing functions, then press
exponential regression model does not need to be converted to the form y = ae
Remember to clear or deselect the plot before viewing graphs of other functions.
5.6.1 Making a Matrix: The TI-92 can work with as many different matrices as the memory will hold. Here's how


to create this 3×4 matrix



From the Home screen, press APPS 6[Data/Matrix Editor] 3[New]. Set the Type to Matrix, the Variable to a (this
is the 'name' of the matrix), the Row Dimension to 3 and the Col Dimension to 4 (Figure 5.74). Press ENTER to
accept these values.
2 6
Graphing Technology Guide: TI-92
1985 1986 1987
4850 4936 5024
x
. To get this exponential growth model press F5[Calc] and set the Calculation Type
Figure 5.73: Exponential growth model
GRAPH to graph the exponential growth model. Note that the
5.6 Matrices
−

1 4 3 5

− − −
1 3 1 3 in your calculator.


−
2 0 4 6

Copyright © Houghton Mifflin Company. All rights reserved.
1988 1989 1990
5112 5202 5294
cx
. The exponential regression that the TI-92 will
x
). To convert this to the form y =
cx
before graphing.
1991 1992
5384 5478
x ln 1.017454
or y =
Y= and inactivate or clear