## anonymous 3 years ago matrices

1. anonymous

$x_1+2x_2+x_3=5$ $4x_1+7x_2+8x_3=9$ $2x_1+3x_2+5x_3=1$ a) write the system in a matrix multiplication AX=Y

2. anonymous

is it $\left[\begin{matrix}1 & 2 &1\\ 4 & 7& 8\end{matrix}\right]\left[\begin{matrix}x_1 \\ x_n\end{matrix}\right]=\left[\begin{matrix}5 \\ 9\\1\end{matrix}\right]$

3. anonymous

hmm you missed one rown in the end in the A matrix.

4. anonymous

5. UnkleRhaukus

$\left[\begin{matrix}1 & 2 &1\\ 4 & 7& 8\\2&3&5\end{matrix}\right]\left[\begin{matrix}x_1 \\ x_2\\x_3\end{matrix}\right]=\left[\begin{matrix}5 \\ 9\\1\end{matrix}\right]$

6. anonymous

oh yes thank you how do we find the det(A) Adj(A)