As more and more high quality software apps are appearing for the TI-83 Plus calculator, I have begun to wonder if there is anything that these amazing devices

cannotbe programmed to do! I must confess, one of my wish-list items for a long time now has been some computer algebra capabilities: I suppose I have been guilty of a little computer algebra-envy after using the wonderful and very powerful TI-89 and new Voyage™ 200. My enquiries to Texas Instruments, however, have been firm: no, there are no plans to develop symbolic algebra for the 83 Plus. A little disappointed by this, I decided to take matters into my own hands.The nice people at

Detached Solutions(http://www.detachedsolutions.com) have written some wonderful Apps for the 83Plus, including one calledSymbolic. As the name implies, this adds basic symbolic algebra capabilities to the 83 Plus: in particular, aSIMPcommand to perform simplification and expansion of algebraic expressions, and a symbolic differentiation command,D. These functions operate on string variables: i.e. they require inverted commas around the input. This makes them a little awkward to use, and the output tends to look a little messy.Fortunately, when combined with another App, called

PrettyPrint(also available fromDetachedSolutionsbut written bySoftTheissathttp://www.softheiss.com) this problem disappears.PrettyPrintdoes what it promises and presents algebraic expressions in correct formatting, making it easy for students at all levels to interpret their algebraic output.These two apps can work seamlessly together, but to make the process even easier, I wrote a couple of TI-BASIC programs which offer a simple front-end for teachers and students who would like to add some alg capabilities to their 83 Plus calculators.

ALG83takes an expression (or allows the user to pick up whatever is inY1), presents it correctly and then offers a choice of options: simplify (or expand), substitute a value, differentiate or view the function using table of values or graph. It also links directly with a second program for equation solving.

EQNSOLVtakes the left-hand and right-hand sides of an equation (or usesY1andY2if desired) and offers the choice of a “fast solve” (using the in-builtSOLVEcommand, or a step-by-step linear equation solver.

In the example shown, the first step would be to

SIMPLIFY, expanding the left-hand side. From the menu shown, choosing 2 produces a simpler form.Next step involves, perhaps, taking 3

xfrom both sides, so the user enters–3X.This is automatically simplified to give the next step of the process. In this way, students may work through the equation solving process, supported by the software until they are capable of working unassisted.

So what algebra did you want to be able to do with your high school students: simplify, expand, substitute, solve equations, even some calculus? It is all here. Have fun!

Email me atsteve.arnold@tpg.com.auwith comments or suggestions, and visithttp://www.detachedsolutions.comto download the FREE apps available there.

For comments & suggestions, please e-mail Steve Arnold.