On the augmented matrix A below , perform all three row operations in the order
given,
((a) followed by (b) followed by
(c)) and then write the resulting augmented matrix.

A = \displaystyle\left[\begin{array}{rrr|r}
1 &2 &6 &-4 \cr
1 &3 &3 &-1 \cr
-3 &-7 &1 &-1 \cr
\end{array}\right]

(a) R_2 = -1 r_1 + r_2

(b) R_3 = 3 r_1 + r_3

(c) R_3 = 1 r_2 + r_3

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