SOLUTION: a=[3-2-3],[2-10],[23-1] find the inverse of the matrix. This is the answer I came up with and I think it is wrong. I have done this a few times and get a different answer every tim

Algebra ->  Matrices-and-determiminant -> SOLUTION: a=[3-2-3],[2-10],[23-1] find the inverse of the matrix. This is the answer I came up with and I think it is wrong. I have done this a few times and get a different answer every tim      Log On


   

Question 547541: a=[3-2-3],[2-10],[23-1] find the inverse of the matrix. This is the answer I came up with and I think it is wrong. I have done this a few times and get a different answer every time. This was what I had for the last try:
[0/42/4-8/4],[3/49/45/4],[-3/43/45/4]. Can you tell what I have done wrong?
Answer by KMST(5397) About Me  (Show Source):
You can put this solution on YOUR website!
I assumed that the matrix you are talking about is
A=%28%0D%0A+matrix%28+3%2C+3%2C+%0D%0A+++3%2C-2%2C-3%2C2%2C-1%2C0%2C2%2C3%2C-1%29%0D%0A%29
One way of finding the inverse is A%5E-1=adj%28A%29%2Fdet%28A%29, which involves calculating the determinant det%28A%29 and the matrix adj%28A%29.
Calculating det%28A%29 is complicated and you may make mistakes.
Calculating the matrix adj%28A%29 is much worse.
I calculated det(A)=-25 and

Amazingly, it checks. (I usually make mistakes in complicated calculations).
I cannot figure out where you could have made a mistake. Not enough information. I do not even know if your matrix is the same one I used. The inverse you calculated has 4 as denominator everywhere, so I imagine that you calculated the determinant of your matrix as 4.
If you search the internet for matrix inverse, you will find plenty of online explanations and instructions. There are online matrix calculators too, that will give you determinants, inverses, and more. Maybe you can use those to help yourself. It is likely to work better than trying to diagnose your problem through questions in this website.