To type in your matrix, state the size and then type the entries from left to right, top to bottom. To row reduce a matrix, use the command .rref().

Beware: even though we generally type numbers into a matrix using rows, you'll almost always want to think of vectors as columns.

<sagecell> A=matrix(3,4,[1,1,2,7,1,2,3,9,2,1,4,15])

R=A.rref() #Compute the rref

1. The commands below put the output into a nice table.

table([ ["$A$", A], ["Reduced Row Echelon Form", R], ]) </sagecell>

There are other ways to enter an augmented matrix.

<sagecell> A=matrix([ [1,1,2,7], [1,2,3,9], [2,1,4,15] ])

A.rref() #Compute the rref

</sagecell>

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