Cramer's Rule: setting up determinants, which to use

Linear spaces and subspaces, linear transformations, bases, etc.
testing
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Cramer's Rule: setting up determinants, which to use

Postby testing » Thu Jan 22, 2009 3:29 pm

When you're doing Cramer's Rule, like if you have three equations in three unknowns, then you'll have four matrixes that you have to find the determinants of. Is there any easy way to remember how to set those up, and which to use for finding what variable?

Thnx

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stapel_eliz
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Postby stapel_eliz » Thu Jan 22, 2009 8:21 pm

Try reviewing the pictures here.

In words: Pick the variable you want to solve for. Take the other-side-of-the-"equals" column, and insert that column of values in place of the column (in the augmented matrix) representing that variable. Find the value of that determinant. Divide by the value of the determinant of the original augmented matrix. The result is the value of the variable you picked.

And that's all there is to it! :thumb:

Eliz.

testing
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Re: Cramer's Rule: setting up determinants, which to use

Postby testing » Sat Jan 31, 2009 8:13 pm

That was easier to remember than what they had in the book. Thnx


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