Display more than just one root

[Tim Wessman]

Hello,

The solve application is a purely numerical solver. It will only give you the nearest unique answer from your initial guess. You can use the PLOT key which can show you nearby results as well.

For example, type X^3+3*X^2-1=Y in your solve. Press NUM and type 0 for your Y. Type 1 for X. Now when you press solve, it uses the initial value for X and iterates to find the root. If you started at -10, it would give you a different result. Press PLOT and you'll see intersections of your lines.


Now if you are wanting to get results all together, you can also do this - just by doing it the same way as what your friend is doing.

Go to the CAS screen, type your equation, and use the TOOLBOX->CAS->Solve -> Numerical Solve command. You should see something like:

fsolve(x^3+3*x^2-1) [ENTER] [-1, -1.618... .618...]

There are your three results. Note that since this is a numeric solver, you cannot always guarantee that ALL possible results have been returned for many types of systems. You can however specify ranges. For example:


fsolve(x^3+3*x^2-1,x,0..1) [ENTER] [.618...] (from range 0 to 1)

fsolve(x^3+3*x^2-1,x,-1..1) [ENTER] [ -1, .618...] (from range -1 .. 1)


So basically, on the nspire you have the "solve" command. If it can't symbolically solve something, it will automatically drop back to numeric solving. On Prime, you have separate numeric and symbolic commands (fsolve, solve).