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Mirrors > Home > ILE Home > Th. List > xnegeq | GIF version |
Description: Equality of two extended numbers with -𝑒 in front of them. (Contributed by FL, 26-Dec-2011.) (Proof shortened by Mario Carneiro, 20-Aug-2015.) |
Ref | Expression |
---|---|
xnegeq | ⊢ (𝐴 = 𝐵 → -𝑒𝐴 = -𝑒𝐵) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqeq1 2146 | . . 3 ⊢ (𝐴 = 𝐵 → (𝐴 = +∞ ↔ 𝐵 = +∞)) | |
2 | eqeq1 2146 | . . . 4 ⊢ (𝐴 = 𝐵 → (𝐴 = -∞ ↔ 𝐵 = -∞)) | |
3 | negeq 7955 | . . . 4 ⊢ (𝐴 = 𝐵 → -𝐴 = -𝐵) | |
4 | 2, 3 | ifbieq2d 3496 | . . 3 ⊢ (𝐴 = 𝐵 → if(𝐴 = -∞, +∞, -𝐴) = if(𝐵 = -∞, +∞, -𝐵)) |
5 | 1, 4 | ifbieq2d 3496 | . 2 ⊢ (𝐴 = 𝐵 → if(𝐴 = +∞, -∞, if(𝐴 = -∞, +∞, -𝐴)) = if(𝐵 = +∞, -∞, if(𝐵 = -∞, +∞, -𝐵))) |
6 | df-xneg 9559 | . 2 ⊢ -𝑒𝐴 = if(𝐴 = +∞, -∞, if(𝐴 = -∞, +∞, -𝐴)) | |
7 | df-xneg 9559 | . 2 ⊢ -𝑒𝐵 = if(𝐵 = +∞, -∞, if(𝐵 = -∞, +∞, -𝐵)) | |
8 | 5, 6, 7 | 3eqtr4g 2197 | 1 ⊢ (𝐴 = 𝐵 → -𝑒𝐴 = -𝑒𝐵) |
Colors of variables: wff set class |
Syntax hints: → wi 4 = wceq 1331 ifcif 3474 +∞cpnf 7797 -∞cmnf 7798 -cneg 7934 -𝑒cxne 9556 |
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 603 ax-in2 604 ax-io 698 ax-5 1423 ax-7 1424 ax-gen 1425 ax-ie1 1469 ax-ie2 1470 ax-8 1482 ax-10 1483 ax-11 1484 ax-i12 1485 ax-bndl 1486 ax-4 1487 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-ext 2121 |
This theorem depends on definitions: df-bi 116 df-3an 964 df-tru 1334 df-nf 1437 df-sb 1736 df-clab 2126 df-cleq 2132 df-clel 2135 df-nfc 2270 df-rex 2422 df-rab 2425 df-v 2688 df-un 3075 df-if 3475 df-sn 3533 df-pr 3534 df-op 3536 df-uni 3737 df-br 3930 df-iota 5088 df-fv 5131 df-ov 5777 df-neg 7936 df-xneg 9559 |
This theorem is referenced by: xnegcl 9615 xnegneg 9616 xneg11 9617 xltnegi 9618 xnegid 9642 xnegdi 9651 xsubge0 9664 xposdif 9665 xlesubadd 9666 xrnegiso 11031 infxrnegsupex 11032 xrminmax 11034 xrminrecl 11042 xrminadd 11044 xblss2ps 12573 xblss2 12574 |
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