Question 471729
{{{(matrix(3,4,1,-2,-9,6,1,-2,-5,2,1,2,15,-14))}}}

~{{{(matrix(3,4,1,-2,-9,6,0,0,4,-4,0,4,24,-20))}}}, after -R1 + R2 and -R1 + R3;

~{{{(matrix(3,4,1,-2,-9,6,0,4,24,-20,0,0,4,-4))}}}, after R2<->R3

~{{{(matrix(3,4,1,-2,-9,6,0,1,6,-5,0,0,1,-1))}}}, after R2/4 and R3/4