Question 869534
{{{(matrix(3,3,3,3,1,1,2,1,2,-1,1))*(matrix(3,1,x,y,z))=(matrix(3,1,1,0,4))}}}
{{{(matrix(3,1,x,y,z))=(1/7)*(matrix(3,3,3,-4,1,1,1,-2,-5,9,3))*(matrix(3,1,1,0,4))}}}
{{{(matrix(3,1,x,y,z))=(matrix(3,1,1,-1,1))}}}