Algebra formulas in Excel

  • Thread starter Thread starter Ovidio
  • Start date Start date
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Ovidio

Is it possible to solve this algebraic system in Excel? If it is, how?
y = 0.6 ( 78.5*x + y) (1)
y = 1.587.500 - 1.296.75*x (2)

Thanks.
 
Hi
you may have a look at 'Tools - Solver' and the Excel help for 'Solver'
to use a search algorithmn to get your x/y value

or just transform both equations and solve it manually.

you may consider using a different type of application for solving such
systems (e.g. Mathematica, Mathlab, etc.)

Note: I think you messed the decimal separator and the 1000 separator
in your second equation
 
Here's a solution I posted earlier to one of the groups.

--
Best Regards
Leo Heuser

Followup to newsgroup only please.


-------------------------------------------
Two simple equations: A=5000+.3B and B=6000+.4A

These can be solved easily on paper (A=7727 and B=9091). How do to this
with a
spreadsheet? I'm using Excel. I have developed a rather ackward model
that
works. I'm hoping someone might be able to suggest a more elegant
approach!GSmith
Click to expand...


GSmith,

You can do it with matrix-operations.

Ordering the equations we get:

A - .3B = 5000
..4 A - B = -6000

Now enter the coefficients of A and B and the numbers in e.g. C8:E9 like
this:

1 -.3 5000
..4 -1 -6000

Solving with matrices is solving the equation X=A^-1*B
where A is the matrix

1 -.3
..4 -1

and B is the matrix

5000
-6000

and A^-1 is A-inverse, which in Excel is found with the formula MINVERSE()

Select e.g. G8 : G9
Enter this formula =MMULT(MINVERSE(C8:D9),E8:E9)
The formula is an array formula and must be entered with
<Shift><Ctrl><Enter> instead og <Enter>, also if edited at a later time.
Having entered it correctly Excel will show the formula in the formula-bar
enclosed in curly brackets { }, and the solution will
be in G8 and G9.

The explanation certainly isn't thorough, but I hope it is enough to get you
started.

Best regards
LeoH
 
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