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Mirrors > Home > ILE Home > Th. List > rexneg | GIF version |
Description: Minus a real number. Remark [BourbakiTop1] p. IV.15. (Contributed by FL, 26-Dec-2011.) (Proof shortened by Mario Carneiro, 20-Aug-2015.) |
Ref | Expression |
---|---|
rexneg | ⊢ (𝐴 ∈ ℝ → -𝑒𝐴 = -𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-xneg 9729 | . 2 ⊢ -𝑒𝐴 = if(𝐴 = +∞, -∞, if(𝐴 = -∞, +∞, -𝐴)) | |
2 | renepnf 7967 | . . . 4 ⊢ (𝐴 ∈ ℝ → 𝐴 ≠ +∞) | |
3 | ifnefalse 3537 | . . . 4 ⊢ (𝐴 ≠ +∞ → if(𝐴 = +∞, -∞, if(𝐴 = -∞, +∞, -𝐴)) = if(𝐴 = -∞, +∞, -𝐴)) | |
4 | 2, 3 | syl 14 | . . 3 ⊢ (𝐴 ∈ ℝ → if(𝐴 = +∞, -∞, if(𝐴 = -∞, +∞, -𝐴)) = if(𝐴 = -∞, +∞, -𝐴)) |
5 | renemnf 7968 | . . . 4 ⊢ (𝐴 ∈ ℝ → 𝐴 ≠ -∞) | |
6 | ifnefalse 3537 | . . . 4 ⊢ (𝐴 ≠ -∞ → if(𝐴 = -∞, +∞, -𝐴) = -𝐴) | |
7 | 5, 6 | syl 14 | . . 3 ⊢ (𝐴 ∈ ℝ → if(𝐴 = -∞, +∞, -𝐴) = -𝐴) |
8 | 4, 7 | eqtrd 2203 | . 2 ⊢ (𝐴 ∈ ℝ → if(𝐴 = +∞, -∞, if(𝐴 = -∞, +∞, -𝐴)) = -𝐴) |
9 | 1, 8 | eqtrid 2215 | 1 ⊢ (𝐴 ∈ ℝ → -𝑒𝐴 = -𝐴) |
Colors of variables: wff set class |
Syntax hints: → wi 4 = wceq 1348 ∈ wcel 2141 ≠ wne 2340 ifcif 3526 ℝcr 7773 +∞cpnf 7951 -∞cmnf 7952 -cneg 8091 -𝑒cxne 9726 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 609 ax-in2 610 ax-io 704 ax-5 1440 ax-7 1441 ax-gen 1442 ax-ie1 1486 ax-ie2 1487 ax-8 1497 ax-10 1498 ax-11 1499 ax-i12 1500 ax-bndl 1502 ax-4 1503 ax-17 1519 ax-i9 1523 ax-ial 1527 ax-i5r 1528 ax-13 2143 ax-14 2144 ax-ext 2152 ax-sep 4107 ax-un 4418 ax-setind 4521 ax-cnex 7865 ax-resscn 7866 |
This theorem depends on definitions: df-bi 116 df-3an 975 df-tru 1351 df-fal 1354 df-nf 1454 df-sb 1756 df-clab 2157 df-cleq 2163 df-clel 2166 df-nfc 2301 df-ne 2341 df-nel 2436 df-ral 2453 df-rex 2454 df-rab 2457 df-v 2732 df-dif 3123 df-un 3125 df-in 3127 df-ss 3134 df-if 3527 df-pw 3568 df-sn 3589 df-pr 3590 df-uni 3797 df-pnf 7956 df-mnf 7957 df-xneg 9729 |
This theorem is referenced by: xneg0 9788 xnegcl 9789 xnegneg 9790 xltnegi 9792 rexsub 9810 xnegid 9816 xnegdi 9825 xpncan 9828 xnpcan 9829 xposdif 9839 xrmaxaddlem 11223 xrminrecl 11236 xrminrpcl 11237 |
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