a={
{1,0,0,0,0,1,1},
{1,3,0,0,3,7,4},
{-2,0,0,0,0,-2,-2},
{0,0,1,0,0,0,-1},
{0,0,0,1,-1,-2,-1}}

MatrixForm[a]

MatrixRank[a]

RowReduce[a]

MatrixForm[%]