SOLUTION: I need to find the inverse of the matrix [ -6 15 ] I tried but it doesn't look right. [ 5 -8 ]

Algebra ->  Matrices-and-determiminant -> SOLUTION: I need to find the inverse of the matrix [ -6 15 ] I tried but it doesn't look right. [ 5 -8 ]      Log On


   

Question 169287: I need to find the inverse of the matrix
[ -6 15 ] I tried but it doesn't look right.
[ 5 -8 ]
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
The inverse of a 2x2 matrix, [A], defined by
%28matrix%282%2C2%2Ca%2Cb%2Cc%2Cd%29%29
is given by
DELTA%2A%28matrix%282%2C2%2Cd%2C-b%2C-c%2Ca%29%29
where
DELTA=%281%2F%28ad-bc%29%29
.
.
.
In your case,
DELTA=%281%2F%28%28-6%29%28-8%29-5%2815%29%29%29
DELTA=%281%2F%2848-75%29%29
DELTA=-%281%2F27%29
-%281%2F27%29%2A%28matrix%282%2C2%2C-8%2C-15%2C-5%2C-6%29%29
%28matrix%282%2C2%2C8%2F27%2C15%2F27%2C5%2F27%2C6%2F27%29%29
%28matrix%282%2C2%2C8%2F27%2C5%2F9%2C5%2F27%2C2%2F9%29%29