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Systems of Linear Equations

Subject: Algebra Problem
Date: Thu, 3 Nov 1994 12:39:21 -0600 (CST)
From: Steve Gardner

It has been some time since I took algebra and my son has asked me the 
following question:

Solve for each system of equations.

x y x-y=5          x + 2y = 10
x+2y=7     &    3x + 4y =  8   x+2y = 10
I can't help.  He is tuned in to the NET today and needs some help with 
this and must show his work.

Could you possibly help?


Date: Thu, 3 Nov 1994 14:12:12 -0500
From: Demetri Bonaros
Subject: Re: Algebra Problem

    Hi, Steve. My name is Demetri and I am one of these math-loving 
College students involved in Dr. Math. Thank you very much for 
writing to us.

    I am sure that we can help you with your son's question; the only
problem is that we (I and another member of the crew) don't quite
understand what these specific equations are [mainly the problem is with
the first equation (x y x-y=5)], or how they are organised (in other words, 
what the two systems are).

    Still, I can give you a pointer that could help you get started: since
this is a simple system of two equations in two unknowns, try solving one
of the two equations in terms of one of the unknowns (for example, you
could subtract 2y from both sides of the equation x + 2y = 10 to get x = 10
- 2y). What you have now is an expression for x. The next step is to
substitute this expression of x in the other equation of the system. Thus,
the second equation will now have only one unknown (namely, y). You can
solve this equation to find the value of y and then you can take this value
and plug it in the expression for x, to find the value of x.

    If you think you need more help, please don't hesitate to write again.

    Demetri, Dr. of some sort.

Subject: Re: Algebra Problem
Date: Thu, 3 Nov 1994 18:24:13 -0600 (CST)
From: Steve Gardner

Dr. Demetri Math

        Thanks for the help.  I don't know how the problem got jumbled up, 
I guess it was my typing.  I guess I need a typing class.  Believe it or 
not, I could solve the problem.  I just wanted Steve, Jr. to see how the 
NET could help him in School as opposed to just tuning into the Dead 
Heads every night.  

        He couldn't imagine that someone like you really was out there and 
willing to help.  From time to time he needs a little push.  Steve is a 
good math student but Geometry is giving him fits.  

        Thanks for the help.  The encouragement you give these kids is 
invaluable.  I hope Steve continues to communicate.

Steve, Sr.
Associated Topics:
High School Linear Equations

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