In this definition, infinitesimal is replaced by a sufficiently small Ax, with the value in the neighborhood of f' (a) calculated as:

f (a + Ax) – f (a)

f' (a) –––––––––––––

Ax

Example

To determine the derivative at x = 3 for the function y = x3 + 4x2 + x – 6

Input the function f(x).

AK4(CALC)2(d/dx)vMde+evx+v-ge

Input point x = a for which you want to determine the derivative.

dw

Using First Derivative Calculation in a Graph Function

•You can omit input of the value a in the syntax on page 2-27 by using the following format for the first derivative graph: Y2 = d/dx (Y1). In this case, the value of the X variable is used instead of the value a.

First Derivative Calculation Precautions

•In the function f(x), only X can be used as a variable in expressions. Other variables

(A through Z excluding X, r, ) are treated as constants, and the value currently assigned to that variable is applied during the calculation.

•Pressing A during calculation of a first derivative (while the cursor is not shown on the display) interrupts the calculation.

•Inaccurate results and errors can be caused by the following:

-discontinuous points in x values

-extreme changes in x values

-inclusion of the local maximum point and local minimum point in x values

-inclusion of the inflection point in x values

-inclusion of undifferentiable points in x values

-first derivative calculation results approaching zero

•Always use radians (Rad mode) as the angle unit when performing trigonometric first derivatives.

•You cannot use a first derivative, second derivative, integration, Σ, maximum/minimum value, Solve or RndFix calculation expression inside a first derivative calculation term.

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