TI-M: Re: Equation question for TI-89


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TI-M: Re: Equation question for TI-89




The problem:
-1 = -1A + 3B
 3 =   2A - 5B

Multiply the top -1 = -1A + 3B by 2

-2 = -2A + 6B
  3 =  2A  - 5B

The add to two to gether:

-2 = -2A + 6B
 
 3 =  2A  - 5B
____________

 1 =           1B
 or
 1 = B
so
subtract 6 from both sides
-2 = -2A + 6
becomes
-8 = -2A
divide both sides by -2
becomes
 4 = A
and
add 5 to both sides
 3 = 2A - 5
becomes
 8 = 2A
divide both sides by 2
becomes
 4 =  A

B =1
A = 4

you know this.

----- Original Message ----- 
From: "BG" <gloverbo@msu.edu>
To: <ti-math@lists.ticalc.org>
Sent: Thursday, September 14, 2000 9:38 PM
Subject: TI-M: Equation question for TI-89


> 
> Hi everybody,
> 
> I'm new to this list. I have a question that probably has an easy
> answer.
> I am about 50 miles away from my TI-89's manual, so unfortunately I
> can't find my answer there.
> 
> PROBLEM:  how can I enter a system of equations into my TI-89 and have
> it solve them?
> For instance:
> 
> -1 = -1A + 3B
> 3 = 2A - 5B
> 
> What do A & B equal?
> 
> This is two equations with 2 unknowns. Isn't there a function to solve
> this? Can't I do this with a Matrix?  If so, could somebody please tell
> me how to do it on a TI-89?  I'm going to need to be able to do it with
> 3 equations and 3 unkowns, also. I have an old Casio that I can do it
> on, but my 89 is a great calculator and I'd like to use it for all my
> needs.
> 
> Thanks!
> 
> B. G.
> 
> 
> 




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