1. ## [Matricies] Finding Inverse?

I don't get it, someone explain?

2. Originally Posted by Cthul

I don't get it, someone explain?
are you sure it's not hence find $\displaystyle A^{-1}$?

3. I'm positive, I have to find the inverse of B somehow.

4. Originally Posted by Cthul
I'm positive, I have to find the inverse of B somehow.
A is the inverse of B.
and B is the inverse of A.

5. Originally Posted by BabyMilo
A is the inverse of B.
and B is the inverse of A.
I don't understand though, it asks me to multiply first and then find the inverse of B.
A isn't a variable is it? 

6. Originally Posted by Cthul
I don't understand though, it asks me to multiply first and then find the inverse of B.
A isn't a variable is it? 
Without performing the multiplication myself, but just based on context (the question plus other posts above me), I'm guessing you'll get the identity matrix.

Originally Posted by Cthul
A isn't a variable is it? 
A is a variable, and it is a matrix. Variables can refer to lots of different mathematical objects, not just real numbers, etc.

7. Originally Posted by Cthul
I don't understand though, it asks me to multiply first and then find the inverse of B.
A isn't a variable is it? 
when u time them together.
you should get
$\displaystyle \begin{bmatrix} 10 & 0 & 0\\ 0 & 10 & 0\\ 0 & 0 & 10 \end{bmatrix}$

you should know$\displaystyle AA^{-1} = \frac{1}{DET} * Identity$

do u understand now?

8. Originally Posted by BabyMilo
when u time them together.
you should get
$\displaystyle \begin{bmatrix} 10 & 0 & 0\\ 0 & 10 & 0\\ 0 & 0 & 10 \end{bmatrix}$

you should know$\displaystyle AA^{-1} = \frac{1}{DET} * Identity$

do u understand now?
So it's
$\displaystyle AB=10I$
$\displaystyle A=10IB^{-1}$
$\displaystyle 1/10*A=B^{-1}$
Right?

9. Originally Posted by Cthul
So it's
$\displaystyle AB=10I$
$\displaystyle A=10IB^{-1}$
$\displaystyle 1/10*A=B^{-1}$
Right?
Looks good to me. I also confirmed the result with Mathematica.