Question

The Matrix c=1 -2 (top)-3 7(bottom) was used to encode a phrase to [7 -28 -25-35-2
-21 107 90 123 17] . find C^_ and use it to decode the matrix.

I need someone to show me how i would decode a matrix. i will become a fan and give a medal to whoever helps me

Answer 1

*the screenshots are easier to understand * I will BECOMe a Fan*

Answer 2

you can encode it using column vectors

Answer 3

i dont know what that is

Answer 4

which one do you want help with, number 13?

Answer 5

yes

Answer 6

ok we want to encode the phrase, one question to go. i believe we want to include spaces.
so we can use a matrix

Answer 7

isn't 1 -2 the matrix ?
-3 7

Answer 8

The idea here is to code it this way
$$
\begin{bmatrix}
1 & -2 \\ -3& 7
\end{bmatrix}
\cdot
\begin{bmatrix}
O & E& Q& E & T & O\\ N &\_ & U & S & I & N
\end{bmatrix}


$$

Answer 9

so what i do next multiply it ?

Answer 10

The idea here is to code it this way
$$
\begin{bmatrix}
1 & -2 \\ -3& 7
\end{bmatrix}
\cdot
\begin{bmatrix}
O & E& Q& E & T & O& \_ &O &G\\ N &\_ & U & S & I & N &T &\_ &O
\end{bmatrix}


$$

Answer 11

do you agree with that so far, we just need to change the letters to numbers now

Answer 12

oh thats all we have to do ?

Answer 13

change to numbers and multiply, yes

Answer 14

okay i think i got it now

Answer 15

but where did you get all those letters from ?

Answer 16

read it down vertically

Answer 17

ok

Answer 18

do i replace the _ with a zero ?

Answer 19

http://prntscr.com/7c1g1p

Answer 20

right

Answer 21

okay i seee lol ....

Answer 22

here is an example http://aix1.uottawa.ca/~jkhoury/cryptography.htm

Answer 23

oh that's what you meant by using column vectors

Answer 24

right, the only difference they used number 27 for _ and we used 0

Answer 25

yeah , so when you decode it ,it'll turn into letters or a phrase

Answer 26

right

Answer 27

okay i understand how to do it , it's going to take me a minute to get my answer soo thanks for helping me understand it .