# Knowledge Base

## Solution 10416: Calculating the Derivative of a Function Using the TI-85 or TI-86.

### How do I calculate the derivative of a function using a TI-85 or TI-86?

To calculate the derivative of a function, refer to the example below:

Example: Find the derivative of x^2 + 2x + 4 when x=2

• On the HOME screen press [2nd] and then the division key (for CALC).
• Press the [F2] key to select nDer (numerical derivative). This will paste nDer( on the HOME screen.
• Type in the example function, x^2 + 2x + 4.
• Insert a comma by pressing the [,] key.
• Type in the variable x by pressing the [x-VAR] key.
• Insert a comma by pressing the [,] key.
• Type in the number 2 by pressing the  key.
• Insert a closed parenthesis by pressing the [)] key.

The HOME screen should show nDer(x^2+2x+4,x,2).

• Press [ENTER].

The HOME screen should show 6. The TI-85 and TI-86 only solve derivatives numerically and will not give the symbolic answer of 2x+2. Instead, the graphing calculator substitutes 2 (for x) into the answer (2x+2) and evaluates the function, hence the answer of 6.