Norm obstruction to being a square
= Norm obstruction to being a square
If $x=y^2$ in a number field, then $N(x)=N(y)^2$; a norm that is not a square in the base field therefore obstructs square roots.
= Norm obstruction to being a square
If $x=y^2$ in a number field, then $N(x)=N(y)^2$; a norm that is not a square in the base field therefore obstructs square roots.