# Re: solving equations with one or more unknowns

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Posted by Brad Paul on September 26, 2002 at 12:17:10:

In Reply to: solving equations with one or more unknowns posted by jeffrey t. hubbard on September 26, 2002 at 10:19:26:

: Math for M/support staff;

: Working on simple equations; Question, when you have one or more unknowns how do you set up the problem to solve for x?
: e.g. 12+ax=16
: b+ax=12
: thanks jeff hubbard
: crazyabtgardenu@aol.com
For a complete solution you need as many equations as you have unknowns.

You have two unknowns and two equations. The following methods will
always work on coupled linear equations but once there are more that
two equations and two unknowns it is well worth your time to learn a
better method.

1) solve one of the two equations for one of the unknowns (say x) in terms of
the other unknown (say y).

2) plug your expression for x into the other equation. Now you only
have an equation in terms of one unknown y.

3) Uniquely solve for y

4) Take your expression for y and plug it into your expression for x
that you got in step 1)

I suggest you try this on a general set of equations like the following:

ax+bx=c
dx+ex=d

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