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Ok, so here goes another problem:

Instructions say to block multiply:

enter image description here

Im stuck at the end where there is clearly something wrong.

Matrix B is: $\begin{bmatrix} 1 & 2 & 0\\ -1 & 1 & 0\\ 0 & 0 & 1\\ 0 & 0 & 3\end{bmatrix}$

..in case its not legible. Sorry for the bad photo :).

1 Answers 1

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In the last block multiplication, you should write $\begin{bmatrix} 0 & 0\end{bmatrix} \left[ 0 \atop 0\right] = 0$ instead of $\begin{bmatrix} 0 & 0 \end{bmatrix} \left[ 0 \atop 0\right] = \begin{bmatrix} 0 & 0 \end{bmatrix}$.