Question

The matrix C=[ ] was used to encode a phrase to [ ]. Find C^-1 and use it to decode the matrix.

I will post a pic of the matrices in the comments. Please help!

Answer 1

@jim_thompson5910 Could you help with this last one as well?

Answer 2

do you know how to find the inverse of a 2x2 matrix?

Answer 3

I'm not exactly sure

Answer 4

Multiply it by its negative?

Answer 5

one sec

Answer 6

If \[\Large X = \begin{bmatrix}a & b\\ c & d \end{bmatrix}\]



Then \[\Large X^{-1} = \frac{1}{ad-bc}\begin{bmatrix}d & -b\\ -c & a \end{bmatrix}\]

Answer 7

Does that formula look familiar?

Answer 8

Yes it does.

Answer 9

So what is the inverse of the given 2x2 matrix?