for(A,1,length(Str1

sub(str1,a,1→str2

if instring("ABCDEFGHIJKLMNOPQRSTUVWXYZ",Str2

Goto 1

End

Disp "no variables"

pause

stop

Lbl 1

Disp "found variable"

Most of the time, you will have only one variable, if you have two, use your graph, so like your example above 250*a+400*b=0, you could change a to x and b to y, giving you 250*x+400*y=0. subtract 400 y on both sides, giving you -400y=250x. Divide 400 on each side, giving you Y=.625x, and it would give you a graph of every possible number.

However, if you only want to find one, the one above would be your best option.

Good Luck,

Mr. Awesomeness

` ``:"{ :For(θ,1,26) :If inString(Str1,sub("ABCDEFGHIJKLMNOPQRSTUVWXYZ",θ,1)) :Ans+sub("ABCDEFGHIJKLMNOPQRSTUVWXYZ",θ,1)+"," :End :sub(Ans,1,length(Ans)-1)`

I know this isn't TI-NSpire Basic, so you might need to use mid() instead of sub() and change Str1 with the name of your own equation string.

Although this may not have been much help, I hope it gives you some ideas. ]]>

I'd like to extract all unknowns from an equation into a list. Let's say I've got the equation

250*a+400*b=0

Given that, basically, I'd like to have a command that simply returns {a, b}

Is there something like that?

Thanks!

Hendrik