New user with a question

[Tim Wessman]

Hello,

This is actually a very interesting equation. It also highlights one of the primary differences between the Prime and the nspire/classpad.

Solving an *exact* symbolic solution for this equation is actually very difficult and requires something called the product log function. Never heard of it? Not surprising. Seems like it was pretty much invented to handle this type of construction where you *can't* define it by simply rearranging things algebraically.

Since none of the calculators support this function however, they can't provide an exact, symbolic result. What the other calculators do then, is just silently begin approximately solving in the background. This is why you end up getting decimal numbers that are *close* to the real result instead of an exact solution like b+sqrt(a+c)/3 or something.

The Prime however will NOT just silently start doing this. You asked it (by using the exact "solve(x^2-2^x,x)" command - the one labeled 1 Solve in your toolbox menu) to generate an exact solution. It first informs you that you didn't provide it an equation, and tells you that it is solving for x^-2^x=0 instead. It can't do so, so it errors and explains why. ("unable to isolate x in ...") You can then change to the numerical solve command, "fsolve(x^2-2^x,x)" (the one labelled 5 Numerical Solve) and it will spit out the results and an explanation of what it was doing.

Which of these is better? Well, that really is a personal preference. However, a lot of people do hold the opinion that anything that stops people from treating the calculator as a "magic box" and helps you think about what you are doing - and more importantly *why* you are doing it - can do nothing but help in math understanding.

The Prime also has significantly more powerful and capable CAS (computer algebra system) compared with either the nspire or classpad. With every CAS you will be able to find an example where it doesn't perform as well as another, but they are huge groups of advanced functionality that only the Prime has included. The others simply don't even try to include it.

One other little tip here. When you have the solve() command up in your entry line, press the HELP button. You'll see some help for the solve command. If you press the "Other" button in the help screen, you will find some related or similar commands. The "Numerical Solve" appears there. You can then jump to the help for that and learn about it.

Neither of the other units have extensive help built into the calculator with a single button press away. :-)