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!

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!

anonymous · Answer

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

jim_thompson5910 · Answer

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

anonymous · Answer

I'm not exactly sure

anonymous · Answer

Multiply it by its negative?

jim_thompson5910 · Answer

one sec

jim_thompson5910 · Answer

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

jim_thompson5910 · Answer

Does that formula look familiar?

anonymous · Answer

Yes it does.

jim_thompson5910 · Answer

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

anonymous · Answer

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