###### Definition3.5.8

If $$A$$ is an $$m\times n$$ matrix, we call the subset of vectors $$\xvec$$ in $$\real^n$$ satisfying $$A\xvec = \zerovec$$ the null space of $$A\text{.}$$ We denote it as $$\nul(A)\text{.}$$

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