Question

I will attach problem.

Answer 1

Have you studied Gaussian Elimination?

Answer 2

\[\left[\begin{matrix}1 & -3 & 2 & 1 \\ -1 & 4 & -4 & 1 \\ 5 & -1 & 6 & 9 \end{matrix}\right]\]

Answer 3

Now use row operations to reduce it to the form:
\[\left[\begin{matrix}1 & 0 & 0 & u1 \\ 0 & 1 & 0 & u2 \\ 0 & 0 & 1 & u3 \end{matrix}\right]\]
Your answer will be (u1, u2, u3)

Answer 4

Your first row already starts with a one so now you have to work on the other 2 rows. Row 2 is easy as well. Just add row 1 to it and it will have the required 0 in front.