Why I should show that no element of $R$ divides both $2$ and $1 + \sqrt{-5}$?
114640
Showing that an ideal is not a free $R-$module.
92599
Prove there generally is no isomorphism between $R[x]/(x^2-a)$ and $R^2$
112043
Show that the ideal $ (2, 1 + \sqrt{-7} ) $ in $ \mathbb{Z} [\sqrt{-7} ] $ is not principal
117999
Prove by contradiction (not using a calculator) that $\sqrt6 + \sqrt2 < \sqrt{15}$?
17542
Why is $\sqrt{-x}*\sqrt{-x}=-x?$
116651
Show for any simple ring without identity, R, that R is a division ring.
3955
Square roots -- positive and negative
143733
Is this proof that $\sqrt 2$ is irrational correct?
113248
Proving $r!$ divides the product of r succesive positive integers
33866
Show that $n$ does not divide $2^n - 1$ where $n$ is an integer greater than $1$?
107765
Prove that there exists two roots in $[-1,1]$
129521
Is $\sqrt[3]{5}$ in $\mathbb Q(\sqrt[3]{2})$?
31555
Divisor of $m$ and $n$ divides $m - qn$ (in proof of Euclidean algorithm)
17926
Zero divisor in $R[x]$
43005
Why does this division result in zero?
114254
Zero divisors in $A[x_1,x_2,\dots,x_r]$
37219
Quadratic Integers in $\mathbb Q[\sqrt{-5}]$