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lesliepeng lesliepeng
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12 years ago
When is it better to use elimination as opposed to the substitution method of solving a system of linear equations?
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wrote...
12 years ago
It depends on how the system is written and how comfortable you are with the methods. If you see a system like

3x + y = 5
-3x + 4y = 11

then it is easy to use elimination because the x terms have opposite coefficients. However, you could also use substitution to solve and get the same answer. The best method is the one that makes the most sense to you.
wrote...
12 years ago
If you can easily cancel out one of the variables either because the problem allows it or you can multiply through each one by a number to make it easy.  You need one of the variables to cancel the other one out so you are left with just one variable to work with.

For ex:

3x +4y = 12
4x - 4y = 24

See how the y's are opposite each other so you can cancel them.  Now if they were both addition you could mult through the second one by a -1 thus creating a situation where the y's would cancel.  If you can "force" one of the variables to cancel without much work elimination is the way to go.
wrote...
12 years ago
If you are good at algebra, substitution is easier. Otherwise, elimination is easier.
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