Identity Matrix: Is Inverse Always True for n>=2?

In summary, an Identity Matrix is a square matrix with 1s along the main diagonal and 0s in all other positions, denoted as I. It has several important properties, such as being the multiplicative identity for matrices and being its own inverse. It is commonly used in linear algebra and is a fundamental concept in many fields. The inverse of an Identity Matrix is always equal to itself, regardless of the size, as long as it is a square matrix. The notation n>=2 refers to the size of the Identity Matrix, and it is important because only square matrices have an inverse. There are no exceptions to the inverse always being true for an Identity Matrix.
  • #1
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Homework Statement



let I_n be as an identity matrix where a_ij = 1 when i=j
I just want to ask that is it true that all identity matrix has an inverse (determinant is not 0) for n>=2?



The Attempt at a Solution

 
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  • #2
The determinant of In is 1, as you can easily compute (expanding along any row or column, you find that det(In) = 1 . det(In - 1) and clearly det(I1) = 1).

Also it is invertible, and it is its own inverse. You can check this directly from the definition.
 

What is an Identity Matrix?

An Identity Matrix, also known as a Unit Matrix, is a square matrix with 1s along the main diagonal and 0s in all other positions. It is denoted as I. For example, a 3x3 Identity Matrix would look like this:

I = [1 0 0; 0 1 0; 0 0 1]

Why is the Identity Matrix important?

The Identity Matrix has several important properties, including being the multiplicative identity for matrices and being its own inverse. It is also used in linear algebra to solve systems of equations, and is a fundamental concept in many other mathematical and scientific fields.

Is the Inverse always true for an Identity Matrix?

For an Identity Matrix of any size, the inverse is always equal to itself. This is because when multiplied by its inverse, the resulting matrix is equal to the original Identity Matrix. In other words, I x I = I.

What is the significance of n>=2 in the context of the Inverse for Identity Matrices?

The notation n>=2 refers to the size of the Identity Matrix, specifically that it is a square matrix with a dimension of 2 or greater. This is important because only square matrices have an inverse, and the inverse of an Identity Matrix is only equal to itself when it is a square matrix.

Are there any exceptions to the Inverse always being true for an Identity Matrix?

No, there are no exceptions to the Inverse always being true for an Identity Matrix. As long as the Identity Matrix is a square matrix, the inverse will always be equal to itself.

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