Question

\[A=\left[\begin{matrix}1 & 0 \\ 3& 2\end{matrix}\right], B=\left[\begin{matrix}x & 0 \\ 1 & 3\end{matrix}\right]\]

and AB=BA find x.

Answer 1

Can you multiply out A*B?

Answer 2

yes

Answer 3

what do you get?

Answer 4

\[\left[\begin{matrix}x & 0 \\ 3x+2 & 6\end{matrix}\right]\]

Answer 5

most excellent.
now do B*A

Answer 6

\[\left[\begin{matrix}x & 0 \\ 10 & 6\end{matrix}\right]\]

Answer 7

now the problem says those two matrices are equal (corresponding elements are equal)
x=x yes
0= 0 yes
6=6 yes
3x+2=10 this one is interesting. solve for x

Answer 8

i see.

Answer 9

uber cool