# Difference Quotient - TI 89 or TI 92

Introduction
This program estimates the value of a derivative at a point using the difference quotient

If you have not used one of the programs posted on this website before, you should read through the information in the Intro to Programming section first.

If you have a TI Connectivity Cable, you can download the program main.diffq.89p

The Program
 :diffq( ) {This will already appear if you named the program diffq} :Prgm {This will already appear} :ClrIO {ClrIO is in the CATALOG menu} :Lbl p {Lbl is in the CATALOG menu} :Local a,h {Local is in the F4 menu} :Input "a=", a {Input is in the F3 menu} { "  is on the  1 button} :Input "h=", h :(y1(a+h) - y1(a))/hd {y1 is the Y button followed by a 1} { is STO} :Disp "estimate", d {Disp is in F3 menu} :Goto p {Goto is in CATALOG menu} :EndPrgm {This will already appear}

Running the Program

You will need to enter a function f(x) into y1 before running the program. To test the program try the following:

f(x)  =  x3,   a=2,   h=0.01.

The answer should be 12.0601