Question

matrix multiplication

Answer 1

ok let's begin first with the general rule of matrix multiplication

Answer 2

\[\left[\begin{matrix}a & b \\ e & f \end{matrix}\right] * \left[\begin{matrix}a' & b' \\ e' & f' \end{matrix}\right]=\left[\begin{matrix}aa'+be' & ab'+b f' \\ ea'+fe' & feb'+ff' \end{matrix}\right]\]

Answer 3

so would it be B

Answer 4

so we take the first line of the matrix on left and we multiply it with the first colonn of the second matrix
such that the first element of the line is multiplied by the first element of the colonn we too
and the second elements of the line multiplide by the second elements of the colonn and so on

Answer 5

ok let's do the maths :)

Answer 6

okay(: one sec let me figure it out!

Answer 7

sorry your problem is not muliplcation problem
so it will be simple !

Answer 8

I though it's A*B
but it's only -5A+4B

Answer 9

\[s*\left[\begin{matrix}a & a \\ c & d\end{matrix}\right]=\left[\begin{matrix}sa & sb \\ sc& sd\end{matrix}\right]\]

Answer 10

so calculate first -5*A and then 4*B I'll give you the answer and then compare it with yours okay

Answer 11

would it be C?

Answer 12

\[-5*A=\left[\begin{matrix}-30 & -5 \\ 20 & 30 \\ -35 & 35\end{matrix}\right]\]

Answer 13

\[4*B=\left[\begin{matrix}-20 & -4 \\ -12& -24 \\ 24 & 32\end{matrix}\right]\]

Answer 14

so now the addition and tell wich answer is correct

Answer 15

@hidy it is a multiplication problem, it just isn't a multiplication of a matrix by a matrix, rather a matrix by a scalar...

Answer 16

im so confused

Answer 17

yes @whpalmer4 you're right! it's multiplication by a scalar :)

Answer 18

okay I'll give you the addition rule
\[\left[\begin{matrix}a & b \\ c & d\end{matrix}\right]+\left[\begin{matrix}e & f \\ g & h\end{matrix}\right]=\left[\begin{matrix}a+e & b+f \\ c+g& d+h\end{matrix}\right]\]

Answer 19

so all you have to do is to add -5*A to 4*B

Answer 20

@kaylaelizabeth is there something not clear ?!!

Answer 21

I am writing the promems down on paper to do it I asked if it was c and you just keep giving me how to do it

Answer 22

ok good so you know how to do it and your answer is correct it's C :)