**Description:** Deduction from real number to complex number. (Contributed by NM, 26-Oct-1999)

Ref | Expression | ||
---|---|---|---|

Hypothesis | recnd.1 | $${\u22a2}{\phi}\to {A}\in \mathbb{R}$$ | |

Assertion | recnd | $${\u22a2}{\phi}\to {A}\in \u2102$$ |

Step | Hyp | Ref | Expression |
---|---|---|---|

1 | recnd.1 | $${\u22a2}{\phi}\to {A}\in \mathbb{R}$$ | |

2 | recn | $${\u22a2}{A}\in \mathbb{R}\to {A}\in \u2102$$ | |

3 | 1 2 | syl | $${\u22a2}{\phi}\to {A}\in \u2102$$ |