Prove the $\ Det A$ is nonzero

50 Views Asked by At

Suppose $A$ is an nxn matrix, then if we have $|Ah|\geq c|h|$ for some positive $c$, can we say $A$ is invertible? Notice that $|.|$ is the Euclidean norm!

1

There are 1 best solutions below

2
On

A matrix is invertible if it has trivial kernel. If for every nonzero $h$ we have $|Ah|\geq c|h|$, in particular $Ah\neq 0$, so $A$ has trivial kernel.