Question

Find the products AB and BA to determine whether B is the multiplicative inverse of A.

Answer 1

A=

Answer 2

B=

Answer 3

A. B = A-1

B. B ≠ A-1

Answer 4

Do you know how to do matrix multiplication?

Answer 5

And do you know what the answer must be for B to be A's multiplicative inverse?

Answer 6

a little bit not good at all.

Answer 7

& no i dont know what the answer must be

Answer 8

\[\left[\begin{matrix}A11&A12&A13\\A21&A22&A23 \\ A31&A32 &A33\end{matrix}\right].\left[\begin{matrix}B11&B12&B13\\B21&B22&B23 \\ B31&B32 &B33\end{matrix}\right]=\left[\begin{matrix}C11&C12&C13\\C21&C22&C23 \\ C31&C32 &C33\end{matrix}\right]\]
A11 is matrix A row 1, column 1, A22 is matrix A row 2 column 2.

You with me?

Answer 9

yea so far

Answer 10

C11 = A11*B11 + A12*B21 + A13*B31
That's the sum of the products of Row 1 of matrix A and Column 1 of B to give you C11.

C12 = A11*B12 + A12*B22 + A13*B32
That's the sum of the products of Row 1 of matrix A and Column 2 of B to give you C12.

For each member of C you just take not it's position then you sum the products of it's equivalent Row in A and the equivalent column in B.

C32 = Row 3 of A and Column 2 of B.

Answer 11

That should be:
For each member of C you just take NOTE OF it's position then you sum the products of it's equivalent Row in A and the equivalent column in B.

Answer 12

okay now im getting a little confused

Answer 13

\[\left[\begin{matrix}.&.&.\\A21&A22&A23 \\ .&. &.\end{matrix}\right].\left[\begin{matrix}.&.&B13\\.&.&B23 \\ .&. &B33\end{matrix}\right]=\left[\begin{matrix}.&.&.\\.&.&C23 \\ .&. &.\end{matrix}\right]\]
C23 = A21*B13 + A22*B23 + A23*B33

I dunno if that makes it more clear.

Answer 14

It can get confusing I know. Took me a while to get this.
Each member of C must be done the same way.

Answer 15

yea it does but were not doing my problem.

Answer 16

Yes we are
What is 1*1 + 0*(-1) + 0*0?

I'm trying to show you how to do it. It's difficult to explain using just 0s and 1s.

Answer 17

oh lol .. its okay but 1!

Answer 18

I'm hoping you can do it yourself now as I need to get back to work. Sorry.

Answer 19

nah ill just get the help tomo