WeBWorK Standalone Renderer

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.

$A = \displaystyle\left[\begin{array}{rrr|r} 1 &2 &6 &-4 \cr 1 &3 &3 &-1 \cr -3 &-7 &1 &-1 \cr \end{array}\right]$
$(a) R_2 = -1 r_1 + r_2$
$(b) R_3 = 3 r_1 + r_3$
$(c) R_3 = 1 r_2 + r_3$

$\left.\vphantom{\begin{array}{c}\!\strut\\\!\strut\\\!\strut\\\!\strut\\\end{array}}\right[$				$\left.\vphantom{\begin{array}{c}\!\strut\\\!\strut\\\!\strut\\\end{array}}\right\|$		$\left.\vphantom{\begin{array}{c}\!\strut\\\!\strut\\\!\strut\\\!\strut\\\end{array}}\right]$

You can earn partial credit on this problem.