Applying rules to simplify a 3 x 3 determinant

In summary, the conversation discusses properties and rules for simplifying the calculation of a 3 x 3 determinant. Specifically, rule (2) and (4) are being discussed and their relationship to linearity. For rule (2), when one row is multiplied by a constant M, the determinant is also multiplied by M. And for rule (4), adding a multiple of one row to another does not change the determinant. This is related to rule (3).
  • #1
PcumP_Ravenclaw
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4
I have attached the properties/rules that will aid in simplifying the 3 x 3 determinant so that it can be calculated with minimum effort. I am trying to understand rule (2) and (4). I am not so clear about the idea of linearity. Can anyone please explain these two rules with regards to example 4.6.6 in the attachment?

Danke..
 

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  • #2
For (2), what happens to the determinant if you multiply one row by a constant M.

Start with

A B C
D E F
G H J

Then multiply one row by M

A B C
MD ME MF
G H J

for example. What happens to the determinant? Linear means this multiplies the determinant by the same M.

As to (4), what it is saying is, if you add some multiple of row 2 to row 1, for example, it will not change the determinant. This is related to (3).
 
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What is a determinant?

A determinant is a mathematical concept used to solve systems of linear equations and determine the properties of a matrix. It is represented by a square array of numbers and can be calculated by following specific rules.

Why do we need to apply rules to simplify a 3 x 3 determinant?

A 3 x 3 determinant can be quite complex to calculate manually, so applying rules can help simplify the process and make it easier to solve. These rules involve performing operations such as multiplying rows or columns by a constant, swapping rows or columns, and adding/subtracting rows or columns.

What are the most commonly used rules for simplifying a 3 x 3 determinant?

The most commonly used rules for simplifying a 3 x 3 determinant include the cofactor expansion method, the rule of Sarrus, and the rule of Laplace. These rules involve manipulating the determinant by using the properties of determinants and matrix operations.

Can these rules be applied to determinants of different sizes?

Yes, the rules for simplifying a 3 x 3 determinant can also be applied to determinants of different sizes, such as 4 x 4 or 5 x 5. However, the process may become more complex and time-consuming as the size of the determinant increases.

Are there any limitations to applying rules to simplify a 3 x 3 determinant?

Yes, there are certain limitations to applying rules for simplifying a 3 x 3 determinant. For example, the rules may not work if the determinant contains zero values, or if the rows or columns are linearly dependent. In such cases, alternative methods may need to be used.

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