Help using TI-89?

[RESmonkey]

I put this in the calc:

solve( x/y=5.6E-10 and x/z=2.2E-11 and x^2/(y*z)=1E-14, {x,y,z})

and get "false."

WTF? I want to find x y and z.

 

[Safeway]

Look in your user manual! Not sure if you need the {} around the x, y, z.

Also, you might have the equation wrong and no such answer exists.

 

[Gerbil333]

Solve by hand?

 

[dighn]

that system doesn't seem to have a solution. try it by hand and you'll see.

 

[RESmonkey]

Argh. It's actually a chem problem I don't understand, and I'm trying to turn it into a few equations that are easier to look at. If anyone remembers equilibrium constant stuff, I'll post the problem here.

 

[TuxDave]

Originally posted by: RESmonkey
I put this in the calc:

solve( x/y=5.6E-10 and x/z=2.2E-11 and x^2/(y*z)=1E-14, {x,y,z})

and get "false."

WTF? I want to find x y and z.

Um.. it doesn't have a solution the way you have it.

 

[enwar3]

can't solve systems of equations i thought

in any case, false means there is no solution

 

[PottedMeat]

Originally posted by: RESmonkey
Argh. It's actually a chem problem I don't understand, and I'm trying to turn it into a few equations that are easier to look at. If anyone remembers equilibrium constant stuff, I'll post the problem here.

Uh I'd say understand the chemistry first than convert it to a strange set of simultaneous equations.

 

[RESmonkey]

I tried. And failed. It's an acid base Ka Kb and Kw kind of problem.

 

[thesurge]

Originally posted by: RESmonkey
I put this in the calc:

solve( x/y=5.6E-10 and x/z=2.2E-11 and x^2/(y*z)=1E-14, {x,y,z})

and get "false."

WTF? I want to find x y and z.

Easy.

Multiply first equation by second equation---> you don't get 1E-14.

 

[RESmonkey]

Kw = Ka x Kb, but using the data given, it doesn't come out to 1E-14. Heh. It's the only question I don't get.

 

[dighn]

Originally posted by: enwar3
can't solve systems of equations i thought

in any case, false means there is no solution

that's a bit cryptic eh? couldn't they just print "no solution"?