Re: Ti92 solver
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Re: Ti92 solver
>From "news.club-internet.fr" <agsd@CLUB-INTERNET.FR>:
> I am trying this equation,
> x+y=5
> x2+y2 = 13
> How can i write on the TI
We haven't yet gotten to the situation of being able to
just "punch the button" for an answer, and I don't think
we ever will. You could issue a solve() command along
with a "with" command (using |) here, but a bit of
_analysis_ first is really helpful. Here's how I would
tackle a system of equations like this on a TI-92:
* Set up x+y=5 --> e1 and x^2+y^2 = 13 --> e2
[Yes, the _equations_ are being stored as variables here.]
* Take a logical first step by entering e1^2 - e2 --> e3 .
The equation e3 displayed should be x*y = 12.
* Now, put e2 - 2*e3 --> e4. The equation e4 is
x^2 - 2x*y + y^2 = -11
Notice that the left hand is the square of x-y, while the
right hand side is -11. Obviously the solutions are going
to be _complex_. You could continue on, on the TI-92, by
taking the square root of e4 and solving along with e1, for
a formal solution, or you could just state the results now
by inspection. There will be two different solutions, but
they are symmetric with respect to each other. With a little
background in the theory of equations, you can state that
the solutions are the roots of the equation W^2-5W-11 = 0.
This sort of "electronic blackboard" approach is how I have
solved similar, tougher problems like the three-equation
system x + y + z = 1, x^2 + y^2 + z^2 = 2, and
x^3 + y^3 + z^3 = 3. And the four- or five-equation analogues
of this system. It gets interesting.
However, I'll bet others on this list have different, very
possibly better, ideas...
RWW Taylor
National Technical Institute for the Deaf
Rochester Institute of Technology
Rochester NY 14623
>>>> The plural of mongoose begins with p. <<<<
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