Theorem xnegeq 13109

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.)

Assertion

Ref	Expression
xnegeq	⊢ (𝐴 = 𝐵 → -𝑒𝐴 = -𝑒𝐵)

Proof of Theorem xnegeq

Step	Hyp	Ref	Expression
1		eqeq1 2733	. . 3 ⊢ (𝐴 = 𝐵 → (𝐴 = +∞ ↔ 𝐵 = +∞))
2		eqeq1 2733	. . . 4 ⊢ (𝐴 = 𝐵 → (𝐴 = -∞ ↔ 𝐵 = -∞))
3		negeq 11355	. . . 4 ⊢ (𝐴 = 𝐵 → -𝐴 = -𝐵)
4	2, 3	ifbieq2d 4503	. . 3 ⊢ (𝐴 = 𝐵 → if(𝐴 = -∞, +∞, -𝐴) = if(𝐵 = -∞, +∞, -𝐵))
5	1, 4	ifbieq2d 4503	. 2 ⊢ (𝐴 = 𝐵 → if(𝐴 = +∞, -∞, if(𝐴 = -∞, +∞, -𝐴)) = if(𝐵 = +∞, -∞, if(𝐵 = -∞, +∞, -𝐵)))
6		df-xneg 13014	. 2 ⊢ -𝑒𝐴 = if(𝐴 = +∞, -∞, if(𝐴 = -∞, +∞, -𝐴))
7		df-xneg 13014	. 2 ⊢ -𝑒𝐵 = if(𝐵 = +∞, -∞, if(𝐵 = -∞, +∞, -𝐵))
8	5, 6, 7	3eqtr4g 2789	1 ⊢ (𝐴 = 𝐵 → -𝑒𝐴 = -𝑒𝐵)

Syntax hints:   → wi 4   = wceq 1540  ifcif 4476  +∞cpnf 11146  -∞cmnf 11147  -cneg 11348  -_𝑒cxne 13011

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1967  ax-7 2008  ax-8 2111  ax-9 2119  ax-ext 2701

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1543  df-fal 1553  df-ex 1780  df-sb 2066  df-clab 2708  df-cleq 2721  df-clel 2803  df-rab 3395  df-v 3438  df-dif 3906  df-un 3908  df-ss 3920  df-nul 4285  df-if 4477  df-sn 4578  df-pr 4580  df-op 4584  df-uni 4859  df-br 5093  df-iota 6438  df-fv 6490  df-ov 7352  df-neg 11350  df-xneg 13014

This theorem is referenced by:  xnegcl  13115  xnegneg  13116  xneg11  13117  xltnegi  13118  xnegid  13140  xnegdi  13150  xsubge0  13163  xlesubadd  13165  xmulneg1  13171  xmulneg2  13172  xmulmnf1  13178  xmulm1  13183  xrsdsval  21317  xrsdsreclblem  21319  xblss2ps  24287  xblss2  24288  xrhmeo  24842  xaddeq0  32697  xrsmulgzz  32964  xrge0npcan  32975  carsgclctunlem2  34293  xnegeqd  45426  xnegeqi  45429  supminfxr2  45458  supminfxrrnmpt  45460  liminflbuz2  45806