Showing $x \in R$ is invertible if and only if $x$ is not contained in any maximal Ideal
137675
Every proper ideal is contained in a maximal ideal, in a commutative ring with identity.
30714
A question on ring homomorphisms and maximal ideals.
113582
How can I find an element $x\not\in\mathfrak mM_{\mathfrak m}$ for every maximal ideal $\mathfrak m$
80827
Let $A$ be a nonempty subset of $\mathbb{R}$. Prove...
74537
Maximal Ideals in $K[y]$
122958
$R/I$ is commutative iff $rs-sr \in I$
464
Prove that the ideal $(X_1-a_1,...,X_n-a_n)$ is maximal in $K[X_1,\dots,X_n]$
64077
$I_m - AB$ is invertible if and only if $I_n - BA$ is invertible.
21604
A complete ring with respect to an ideal
118306
$I:=\{f(x)\in R\mid f(1)=0\}$ is a maximal ideal?
34183
An equivalent condition with $\{0\}$ being the only nilpotent ideal
137450
Two-sided ideal generated by subset of not commutative ring
129371
Maximal ideals in the ring of real functions on $[0,1]$
99715
Proper ideal and units proof
42809
How can we show that $(I-A)$ is invertible?
14873
$1+a$ and $1-a$ in a ring are invertible if $a$ is nilpotent
111996
Maximal and Prime Ideal in Z