inverse matrix?

Question

can someone help me solve this step by step because i dont understand...thanx

|7 2|
|3 1|

how do you find the inverse

Answer 1

First attach the identity matrix behind it.
7 2 | 1 0
3 1 | 0 1
Now you need to make the front part into the identity matrix.
Start by making the first entry in the first row into a one.
Divide the first row by 7
1 2/7 | 1/7 0
3 1 | 0 1
Now you need a zero below the one.
Multiply the first row by -3 and add this to row 2. This will be your new row 2.
1 2/7 | 1/7 0
0 1/7 |-3/7 1
Now you need the second entry of row 2 to be a one. Multiply the second row by 7
1 2/7 | 1/7 0
0 1 | -3 7
Now you need a zero above the one.
Multiply the second rwo by -2/7 and add this to row 1. This will be your new row one.
1 0 | 1 -2
0 1 | -3 7
The inverse is
|1 -2|
|-3 7|
There is a shortcut for finding the inverse of a 2x2 matrix. Do you know it?

Answer 2

Does the matrix I1 1I have an inverse? Please be sure to explain you answer it would be very helpful :)
I2 2I

Answer 3

that should help you

http://mathworld.wolfram.com/MatrixInverse.html