Linear algebra problem with transpose

In summary, the problem asks for a formula for (ABx)T, where x is a vector and A and B are matrices. The relevant formula for this is xTBTAT, which is derived from (AB)T = BTAT. It is possible to use this formula to find a solution without using a lot of summation notation or advanced linear algebra techniques.
  • #1
Bohrok
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Homework Statement



Find a formula for (ABx)T, where x is a vector and A and B are matrices of appropriate sizes.

Homework Equations



(AB)T = BTAT among a few others, probably the most relevant one with transposes here.

The Attempt at a Solution



I'm wondering what this "formula" the problem asks for looks like. I know that (ABx)T = xTBTAT but I can't really see how much simpler another formula might be.

Any ideas what route to take to find a formula for this, preferable without the use of a lot of summation notation or anything beyond a beginning linear algebra course? We used a lot of summations earlier trying to tackle this problem and it just looked messy; I'm hoping there may be a cleaner way of approaching the problem.
 
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  • #2
Perhaps what the question is getting at is for you to use the formula (AB)T = BTAT which you know works for a product of two conformable matrices and get the formula for three of them from that, being careful about properties of matrix multiplication that you know.
 
  • #3
I got it for three matrices and that was before using all the sums. We didn't really go back to the problem again (she said it was so ugly anyway) so I guess that's it for the problem. :) Thanks
 

FAQ: Linear algebra problem with transpose

1. What is the purpose of transposing a matrix in linear algebra?

The transpose of a matrix in linear algebra is used to change the orientation of the matrix, switching the rows and columns. This can be helpful in solving certain problems and performing operations on matrices.

2. How is the transpose of a matrix calculated?

To find the transpose of a matrix, the rows and columns are switched. This means that the first row of the original matrix becomes the first column of the transposed matrix, the second row becomes the second column, and so on.

3. What is the difference between a matrix and its transpose?

A matrix and its transpose have the same elements, but their orientation is different. For example, a 3x4 matrix and its transpose would have the same 12 elements, but the first matrix would have 3 rows and 4 columns, while the transposed matrix would have 4 rows and 3 columns.

4. Can a matrix be transposed more than once?

Yes, a matrix can be transposed multiple times. Each time it is transposed, the rows and columns will switch again, resulting in a different orientation.

5. How is the transpose of a matrix used in real-world applications?

The transpose of a matrix is used in various fields such as engineering, physics, and computer science. It can be used to solve systems of linear equations, perform operations on vectors, and in data analysis and machine learning algorithms.

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