Question

Inverse of the matrix \[\left[\begin{matrix} 11& -5\\2&-1 \end{matrix}
\right]\]
\[-1\left[\begin{matrix} -1& 2\\-5&11 \end{matrix}
\right]\]
=\[\left[\begin{matrix} 1& -2\\5&-11 \end{matrix}
\right]\]

Answer 1

I did the matrix wrong...but what did I do wrong?
@Outkast3r09

Answer 2

you aren't supposed to switch the position of the 2 and -5, only the sign.

Answer 3

can you state the rule for me please? so I would change the position of the 11 and -1 but not the 2 and -5?

Answer 4

right. if the matrix is:

a b
c d

you swap a and d, and change the sign of b and c, so you should get:

d -b
-c a

Then you just divide everything by the determinant.

Answer 5

so it's
1 -5
2 -11
Thanks!