$\displaystyle (i)Q[x]/<x^2+1>$ $\displaystyle is$ $\displaystyle isomorphic$ $\displaystyle to$ $\displaystyle Q[x]/<x^2+x+1>$

$\displaystyle (ii)R[x]/<x^2+1>$ $\displaystyle is$ $\displaystyle isomorphic$ $\displaystyle to$ $\displaystyle R[x]/<x^2+x+1>$

either of the statement is correct. justify your answer.

i think (i) is correct, but i don't know the reason, can you explain please.