Determine whether the system of equation is in row-echelon form.
x-y+3z=-11
y+8z=-12
z=-2
Arrange the coefficients into a 3x3 matrix, filling in zeros for missing values.
A matrix is in row echelon form if
(1) All nonzero rows (rows with at least one nonzero element) are above any rows of all zeroes (if any).
(2) The leading coefficient of a nonzero row is always strictly to the right of the leading coefficient of the row above it.
(3) All entries in a column below a leading entry are zeroes (implied by the first two criteria).
What do you think?