Matrix help!

[fauxjewels]

here are some problems i need help on...

Multiplying matrices!

numbers after 4 and -7 are in matrices ([ ] not big enough!)

4[3 -4 ] + -7[9 -3 ]
7 9 6 -2
- 4 -5 12 9
8 3 -5 3

another problem...
[4 2] X= [1 -3]
3 8 2 6

another problem...

2x-5y+8z=32
2x-5y=32
5x-y=15

 

[soroban]

Hello, fauxjewels!

It's hard to help you if you know nothing about Matrices.
. . like basic addition and scalar multiplication . . .

\(\displaystyle \text{Simplify: }\;\;4\begin{bmatrix}3&\text{-}4\\7&9\\\text{-}4&\text{-}5\\8&3\end{bmatrix} + (\text{-}7)\begin{bmatrix}9&\text{-}3\\6&\text{-}2\\12&9\\\text{-}5&3\end{bmatrix}\)

\(\displaystyle \text{Multiply: }\;\begin{bmatrix}12&\text{-}16\\28&36\\\text{-}16&\text{-}20\\32&12\end{bmatrix}+ \begin{bmatrix}\text{-}63&21\\ \text{-}42&14 \\ \text{-}84&\text{-}63\\35 & \text{-}21\end{bmatrix}\)


. . . . \(\displaystyle \text{Add: }\qquad\quad\begin{bmatrix}\text{-}51&5\\ \text{-}14&50 \\ \text{-}100&\text{-}83 \\ 67&\text{-}9 \end{bmatrix}\)