Row Space

• It is the set of vectors that are outputs of $A^T\vec{x}$.
• It is the span of rows of $A$.

Theorem 28.4

• $\text{Row}(A)$ is a subspace of $R^n$.
• $n$ cuz there are $n$ columns in the transpose of A.
• And a matrix-vector product is basically a linear combination of the columns of the matrix (here, the matrix being a transpose).