How do I graph the logistic function #f(x)=3/(1+4e^(-6x))# on a TI-84?

Question

Lincoln Anderson · Accepted Answer

The TI-84 appears very similar in design and button layout to the TI-83+. Thus, the following steps, as laid out for the TI-83+, are accurate for that calculator.

Press the Y= button, one of the five located directly under the screen, and specifically the one located the farthest to the left. This should take you to the function entry screen.

2) In the "Y1 =" line, input the following: 3/(1+4e^(-6x)). ENSURE that a parenthesis exists grouping the denominator together. The e^ function may be located by first pressing the 2nd button (which switches buttons to their secondary function, and is located directly below the Y= button), and then pressing the button for the natural log (labeled LN, which possesses the secondary function of #e^x#.

Note that you will be given, in your equation, the expression "e^(". Simply input into this parenthesis the power to which e is being raised (in this case, -6x) and then close the parenthesis denoting the exponent. (On the TI-83+, at times the parenthesis will not need to be closed, but it will make the equation appear more properly written and serve as practice should you ever decide to enter mathematical programming, as well as alleviate some confusion).

Once the equation is listed exactly as described in (2), press either the Graph or Trace button, as desired. Graph will simply show you a graph of the function, while Trace will show you a graph and allow you to move along the function with a cursor (again, this is how it is laid out in the TI-83+). From here if you wish, you may press 2nd and then Trace to calculate things like the zeros, minimum and maximum of the function.

James Allen · Answer

undefined To graph the logistic function $ f(x) = \frac{3}{1 + 4e^{-6x}} $ on a TI-84 calculator, follow these steps:

1. Press the "Y=" button to enter the function editor.
2. Enter the function $ \frac{3}{1 + 4e^{-6x}} $ using the following key sequence:
   - Press "3"
   - Press the division symbol "/"
   - Press "("
   - Press "1"
   - Press "+"
   - Press "4"
   - Press "e"
   - Press "^"
   - Press "(-)"
   - Press "6"
   - Press "x"
   - Press ")"
3. Once the function is entered, press the "GRAPH" button to view the graph of the logistic function.

Make sure your calculator is in the correct mode (e.g., RADIAN or DEGREE) depending on the units of your function. You can adjust the window settings (Xmin, Xmax, Ymin, Ymax) if necessary to ensure the graph is properly displayed.