# Calculating determinant of triangular matrix

Provide guidance through an expansion of an nxn determinant where the first column is 0.

I want to expand it in general and show that it is 0 by these constraints:

1: Only being able to expand it along the first row

2: Only determinant ability that you can use is that changing any two rows only changes the determinants sign. It is illustrated a bit further in the attachment

Thank you!

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#### Solution Preview

Hello,

First rearrange ALL the rows in the inverse order:

- change 1-st with n-th

- change 2-nd with (n-1)-th

and so on.

It will be even number ...

#### Solution Summary

This solution provides students with brief but clear guidance on how to expand an nxn determinant where the first column is 0.

$2.19