SOLUTION: Let P = [3 -1] [8 6 ] Determine the inverse of P I am really not sure how to go about this. THANK YOU

Algebra ->  Matrices-and-determiminant -> SOLUTION: Let P = [3 -1] [8 6 ] Determine the inverse of P I am really not sure how to go about this. THANK YOU       Log On


   

Question 1001640: Let
P =
[3 -1]
[8 6 ]
Determine the inverse of P
I am really not sure how to go about this.
THANK YOU
Answer by Edwin McCravy(20059) About Me  (Show Source):
You can put this solution on YOUR website!
%28matrix%282%2C2%2C3%2C-1%2C8%2C6%29%29

1. Find the determinant of the matrix: (3)(6)-(-1)(8) = 18+8 = 26

2. Swap the upper left and lower right elements:
 %28matrix%282%2C2%2C6%2C%22%22%2C%22%22%2C3%29%29

3. Change the signs of the other two elements (upper right
   and lower left:

%28matrix%282%2C2%2C6%2C1%2C-8%2C3%29%29

4. Divide every element by the number obtained in step 1.

%28matrix%282%2C2%2C6%2F26%2C1%2F26%2C-8%2F26%2C3%2F26%29%29

Reduce the reducible fractions:

%28matrix%282%2C2%2C3%2F13%2C1%2F26%2C-4%2F13%2C3%2F26%29%29

The above method only works for finding the inverse of
2x2 matrices.

Edwin