Chapter 4 - Vector Spaces - 4.6 Exercises - Page 239: 12

$dim\,rowA=2$

We are given that matrix A has dimensions 5×6. The matrix is 4-dimensional. Then we have to find the row space of A. $Rank A=n−dim\,NulA$ $n=6$ and $dim\,NulA=4$ $RankA=6-4=2$ the rank of a matrix is equal to the number of pivot rows. the number of pivot rows is equal to the dimension of the row space of $A=2$. the dimension of the row space of $A=2$