# Equivalence theorem for nonsingular matrices: the equation Ax=0 has only the trivial solution.

Put content here**Theorem:** An $n \times n$ matrix $A$ is nonsingular if and only if $Ax = 0$ has only the **trivial solution** $x = 0$.
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**Proof:** If $A$ is nonsingular, $x = A^{-1}0 = 0$. Conversely, if only $x = 0$ solves $Ax = 0$, then the null space is $\{0\}$, so nullity is 0, so rank is $n$, so columns are linearly independent, so $A$ is nonsingular.

# Parents

* Nonsingular matrices and equivalences