Question

For problems 13 and 14, assign each letter and a blank space to a number as shown by the alphabet table below.

alphabet table

0 = _ 1= A 2 = B 3 = C 4 = D 5 = E 6 = F 7 = G 8 = H 9 = I 10 = J 11 = K 12 = L 13 = M 14 = N 15 = O 16 = P 17 = Q 18 = R 19 = S 20 = T 21 = U 22 = V 23 = W 24 = X 25 = Y 26 = Z

use the matrix [1,-2]
[-3,7] encode the phrase "ONE QUESTION TO GO"

Answer 1

@jim_thompson5910 can you help please?

Answer 2

Sorry for some reason in that last one, I put it as a 9x2 matrix when it *should* be a 2x9 matrix

Answer 3

ONE_QUESTION_TO_GO turns into the number sequence

15 , 14 , 5 , 0 , 17 , 21 , 5 , 19 , 20, 9 , 15 , 14 , 0 , 20 , 15 , 0 , 7 , 15

which breaks down like this into 2 rows (9 numbers each)

15 , 14 , 5 , 0 , 17 , 21 , 5 , 19 , 20,
9 , 15 , 14 , 0 , 20 , 15 , 0 , 7 , 15

Answer 4

So you really have to multiply out these 2 matrices

\[\large
\begin{bmatrix}
1 & -2\\
-3 & 7
\end{bmatrix}
\begin{bmatrix}
15 & 14 & 5 & 0 & 17 & 21 & 5 & 19 & 20\\
9 & 15 & 14 & 0 & 20 & 15 & 0 & 7 & 15
\end{bmatrix}
\]

Answer 5

the same principles of matrix multiplication apply but now you'll have a 2x9 matrix for the answer

Answer 6

will the numbers be the same but just in a different order? lol bc i just did allll that multiplying for the first go. doing it again would kill -.-

Answer 7

well in row1, column1 of matrix C you'd multiply row 1 of A with column 1 of B to get

1*15 + (-2)*9 = 15 - 18 = -3

So our 2x9 answer matrix C starts off with 18 blank slots (call them x for now)

\[\large
C =
\begin{bmatrix}
x & x & x & x & x & x & x & x & x\\
x & x & x & x & x & x & x & x & x
\end{bmatrix}
\]

and we replace the x in row1, column1 with -3
\[\large
C =
\begin{bmatrix}
-3 & x & x & x & x & x & x & x & x\\
x & x & x & x & x & x & x & x & x
\end{bmatrix}
\]

Answer 8

multiply row1 of A with column 2 of B:

1*14 + (-2)*15 = 14 - 30 = -16

this result goes in row1, column2 of C

\[\large
C =
\begin{bmatrix}
-3 & -16 & x & x & x & x & x & x & x\\
x & x & x & x & x & x & x & x & x
\end{bmatrix}
\]

Answer 9

okay i see. so im gonna try and multiply out this thing and then i will show you for you to check.is that okay?

Answer 10

sure I can do that

Answer 11

lol okie dokie sooo i got

-3 , -16 , -23 , 0 , -23 , -9 , 5 , 5 , -10
18 , 63 , 83 , 0 , 89 , 42 , -15 , -8 , 45

Answer 12

I'm getting the same, so nice work

Answer 13

yay awesome !