QUESTION $1$a: $($BY HAND$)$ Solve the following system using Gauss elimination algorithm and explain the steps $($i$.$e$.$ the elementary row operations$)$ you followed to get the solution.

$x_1+3x_2+x_3,=1$

$-4x_1-9x_2+2x_3,=-1$

$0x_1-3x_2-6x_3,=-3$

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