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## HOW TO FIND NUMERICAL DERIVATIVES WITH TI89 CALCULATOR

 Method 1: Using d() function on Home screen Steps Key Sequence Screens 1. Set Up Differentiator Press F3, then ALPHA key, then = key (for nDeriv() 2. Type the Function 3. Input Variable Press comma, then the variable 4. Input Value for h Press comma, then 0.01 (or smaller) NOTE: The default value for h is 0.001 4. Execute Derivative Press ')', then ENTER Method 2: Using graph of function Steps Key Sequence Screens 1. Input Function, Piecewise-Defined Function, or Parametric Equation. Press DIAMOND key, then F1 key (for Y=) Type the function 2. Graph Press DIAMOND key, then F3 key 3. Find Derivative Press F5 Press 6 (for Derivatives) Select appropriate derivative Type in value for x or trace function until you reach the value for x. Note: For a parametric equation: type in value for t or trace curve until you reach the value for t. Note: In this case, we are finding the derivative of the function at x = 1. Press ENTER Note: In this case, the derivative of the function at x = 1 is dy/dx = –1.