Taught Identity and Inverse Matrix for my 5 KA class today. Glad to see most of them are able to find the inverse of a 2 x 2 matrix. Sadly there are some girls who are not interested at all in learning. It's not easy being a teacher, having to deal with all sorts of students. There are those who are very bright and self motivated. I don't have to worry about them. Then there's those who are slower but willing to learn. I enjoy being able to help them. Then there are those who's not interested at all, that's where my headache is. How to make them interested in learning???? Any ideas?? Sometimes I do wonder what they think about when they're in school. The sad thing is I know that they're capable of better things but they're are not willing to try. Enough of my ramblings, I'm suppose to write on the lesson that I did today :

Identity Matrix (I)

A square matrix in which all the main diagonal elements are 1’s and all the remaining elements are 0’s is called an Identity Matrix.

# Identity Matrix is denoted with the letter “In×n”, where n×n represents the order of the matrix.

# One of the important properties of identity matrix is: A×In×n = A, where A is any square matrix of order n×n.

Example

2 x 2 Identity Matrix

3 x 3 Identity matrix

n x n Identity matrix

Inverse Matrix

For a square matrix A, the inverse is written A-1. When A is multiplied by A-1 the result is the identity matrix, I.

AA-1 = A-1A = I

Example: For matrix A = ,

its inverse is

since AA-1 =

and A-1A =

Please do all the assignment given so that we can discuss the answers next week.

## Monday, April 27, 2009

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TEACHERRR !! jo leen heree :D:D ! keep it up teacher ! :D

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