# Calculating the value of determinant by using row-column tri

• navneet9431
In summary, the conversation is about finding the value of a determinant using a specific method. The person asking for help is getting a wrong result and is advised to make sure the column operations are done sequentially and using the updated columns in each step.
navneet9431
Gold Member

## Homework Statement

I am trying to find the value of a determinant,

## Homework Equations

See the notes given in my Textbook,

## The Attempt at a Solution

I applied this method to find the value of a determiannt,

See it here,

Why is my result wrong?

I will be thankful for any help!

#### Attachments

• IMG_20180803_122649.jpg
55.7 KB · Views: 692
• IMG_20180803_122742.jpg
38.4 KB · Views: 638
• IMG_20180803_122102.jpg
66.9 KB · Views: 418
The column operations must be done sequentially, and at each step must use the columns from the new matrix created in the previous step.

So in the second step when you subtract C2 from C3 it has to be the new C2, not the original one.

navneet9431
Thanks !
andrewkirk said:
The column operations must be done sequentially, and at each step must use the columns from the new matrix created in the previous step.

So in the second step when you subtract C2 from C3 it has to be the new C2, not the original one.

## 1. How do I calculate the value of a determinant using the row-column tri method?

The row-column tri method, also known as the Sarrus method, involves creating a grid with the given matrix and then multiplying diagonally downwards and upwards. Add the two products together and subtract the sum of the diagonally upwards products from the sum of the diagonally downwards products.

## 2. What is the purpose of using the row-column tri method to calculate determinants?

The row-column tri method is a systematic way of calculating determinants for larger matrices. It is useful because it is a straightforward and efficient process that can be used for any size matrix.

## 3. Can the row-column tri method be used for non-square matrices?

No, the row-column tri method can only be used for square matrices, which have an equal number of rows and columns. For non-square matrices, other methods such as Gaussian elimination or the cofactor expansion method must be used to calculate the determinant.

## 4. Are there any limitations to using the row-column tri method?

One limitation of the row-column tri method is that it can become more time-consuming and complicated for larger matrices. In these cases, it may be more efficient to use other methods or a computer program to calculate the determinant.

## 5. Are there any tips for avoiding errors when using the row-column tri method?

It is important to be careful when multiplying and adding the products in the grid, as mistakes can easily be made. Double-checking your work and using a calculator can help prevent errors. It is also helpful to break down larger matrices into smaller ones to make the process more manageable.

• Precalculus Mathematics Homework Help
Replies
1
Views
676
• Precalculus Mathematics Homework Help
Replies
32
Views
1K
• Precalculus Mathematics Homework Help
Replies
11
Views
1K
• Precalculus Mathematics Homework Help
Replies
5
Views
4K
• Precalculus Mathematics Homework Help
Replies
9
Views
3K
• Precalculus Mathematics Homework Help
Replies
4
Views
1K
• Precalculus Mathematics Homework Help
Replies
18
Views
1K
• Precalculus Mathematics Homework Help
Replies
2
Views
1K
• Precalculus Mathematics Homework Help
Replies
5
Views
2K
• Precalculus Mathematics Homework Help
Replies
9
Views
3K