**Description:** Addition of a number and its negative. (Contributed by NM, 26-Nov-1994)

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

Hypothesis | negidi.1 | $${\u22a2}{A}\in \u2102$$ | |

Assertion | negidi | $${\u22a2}{A}+\left(-{A}\right)=0$$ |

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

1 | negidi.1 | $${\u22a2}{A}\in \u2102$$ | |

2 | negid | $${\u22a2}{A}\in \u2102\to {A}+\left(-{A}\right)=0$$ | |

3 | 1 2 | ax-mp | $${\u22a2}{A}+\left(-{A}\right)=0$$ |