Answer:
Hello,
Answer m=-1, n=-6,l=2
Step-by-step explanation:
[tex]A*U=B\\\begin{bmatrix}3&-1&0\\0&1&3\\0&0&2\end{bmatrix}*\begin{bmatrix}m\\n\\l\end{bmatrix}=\begin{bmatrix}3\\0\\4 \end{bmatrix}\\\\\\A^{-1}=\begin{bmatrix}\dfrac{1}{3}&\dfrac{1}{3}&\dfrac{-1}{2}\\\\0&1&\dfrac{-3}{2} \\\\0&0&\frac{1}{2}\end{bmatrix}\\\\\\A^{-1}*A*U=A^{-1}*B\\[/tex]
[tex]U=\begin{bmatrix}\dfrac{1}{3}&\dfrac{1}{3}&\dfrac{-1}{2}\\\\0&1&\dfrac{-3}{2}\\\\0&0&\dfrac{1}{2}\end{bmatrix}*\begin{bmatrix}3\\0\\4\\\end{bmatrix}=\begin{bmatrix}-1\\-6\\2\end{bmatrix}\\\\[/tex]
