Complex numbers

The complex numbers $ℂ$ are the Algebraic closure of $ℝ$ #m/def/complex given by adjoining a single root of unity $𝑖$ such that $𝑖 2 = - 1$ , i.e.

ℂ = ℝ [𝑖]

Equivalently, $ℂ$ is the metric completion of the field of algebraic numbers $―― ℚ$ .

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