real analysis - dedekind cut for the square root

Can somebody give me the hints to solve it ?

1. What is the Dedekind cut $(A, B)$ for $\sqrt 2$ ?



2. What is the Dedekind cut $(C, D)$ for
   $\sqrt 2 + \sqrt 3$ ?


3. In $\mathbb R[x]/(x^2 + 1)$, what is the value of $[x^3 + x^2 + x + 1]$?
   (Just simplify $x^3 + x^2 + x + 1$)
   where $[p]$ means the equivalence class that has $p$ as an element;
   $[p]$ is the set of polynomials $q$ in $\mathbb R[x]$ such that
   $x^2 + 1$ divides $p - q$.
   $\mathbb R[x]$ is the set of polynomials whose coefficients are all real numbers.