Let $(R,+,·)$ be a non-commutative ring. If $a\in R$ is invertible, and $x\in R$ is non-invertible, does that imply that $ax$ is non-invertible?
2026-03-26 11:04:58.1774523098
Invertibility of the product of two elements in a ring
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If $ax$ was invertible then lets call the inverse $y$. $$yax = axy = e $$
Now lets multiply by $a^{-1}$ $$a^{-1}yax = xy =a^{-1}$$
Now multiply by $a$
$$xya = e$$
Therefore $x^{-1} = ya$