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Theorem subsub4 7307
Description: Law for double subtraction. (Contributed by NM, 19-Aug-2005.) (Revised by Mario Carneiro, 27-May-2016.)
Assertion
Ref Expression
subsub4  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  (
( A  -  B
)  -  C )  =  ( A  -  ( B  +  C
) ) )

Proof of Theorem subsub4
StepHypRef Expression
1 nppcan2 7305 . 2  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  (
( A  -  ( B  +  C )
)  +  C )  =  ( A  -  B ) )
2 simp1 915 . . . 4  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  A  e.  CC )
3 simp2 916 . . . 4  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  B  e.  CC )
4 subcl 7273 . . . 4  |-  ( ( A  e.  CC  /\  B  e.  CC )  ->  ( A  -  B
)  e.  CC )
52, 3, 4syl2anc 397 . . 3  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  ( A  -  B )  e.  CC )
6 simp3 917 . . 3  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  C  e.  CC )
73, 6addcld 7104 . . . 4  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  ( B  +  C )  e.  CC )
8 subcl 7273 . . . 4  |-  ( ( A  e.  CC  /\  ( B  +  C
)  e.  CC )  ->  ( A  -  ( B  +  C
) )  e.  CC )
92, 7, 8syl2anc 397 . . 3  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  ( A  -  ( B  +  C ) )  e.  CC )
10 subadd2 7278 . . 3  |-  ( ( ( A  -  B
)  e.  CC  /\  C  e.  CC  /\  ( A  -  ( B  +  C ) )  e.  CC )  ->  (
( ( A  -  B )  -  C
)  =  ( A  -  ( B  +  C ) )  <->  ( ( A  -  ( B  +  C ) )  +  C )  =  ( A  -  B ) ) )
115, 6, 9, 10syl3anc 1146 . 2  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  (
( ( A  -  B )  -  C
)  =  ( A  -  ( B  +  C ) )  <->  ( ( A  -  ( B  +  C ) )  +  C )  =  ( A  -  B ) ) )
121, 11mpbird 160 1  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  (
( A  -  B
)  -  C )  =  ( A  -  ( B  +  C
) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 102    /\ w3a 896    = wceq 1259    e. wcel 1409  (class class class)co 5540   CCcc 6945    + caddc 6950    - cmin 7245
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-in1 554  ax-in2 555  ax-io 640  ax-5 1352  ax-7 1353  ax-gen 1354  ax-ie1 1398  ax-ie2 1399  ax-8 1411  ax-10 1412  ax-11 1413  ax-i12 1414  ax-bndl 1415  ax-4 1416  ax-14 1421  ax-17 1435  ax-i9 1439  ax-ial 1443  ax-i5r 1444  ax-ext 2038  ax-sep 3903  ax-pow 3955  ax-pr 3972  ax-setind 4290  ax-resscn 7034  ax-1cn 7035  ax-icn 7037  ax-addcl 7038  ax-addrcl 7039  ax-mulcl 7040  ax-addcom 7042  ax-addass 7044  ax-distr 7046  ax-i2m1 7047  ax-0id 7050  ax-rnegex 7051  ax-cnre 7053
This theorem depends on definitions:  df-bi 114  df-3an 898  df-tru 1262  df-fal 1265  df-nf 1366  df-sb 1662  df-eu 1919  df-mo 1920  df-clab 2043  df-cleq 2049  df-clel 2052  df-nfc 2183  df-ne 2221  df-ral 2328  df-rex 2329  df-reu 2330  df-rab 2332  df-v 2576  df-sbc 2788  df-dif 2948  df-un 2950  df-in 2952  df-ss 2959  df-pw 3389  df-sn 3409  df-pr 3410  df-op 3412  df-uni 3609  df-br 3793  df-opab 3847  df-id 4058  df-xp 4379  df-rel 4380  df-cnv 4381  df-co 4382  df-dm 4383  df-iota 4895  df-fun 4932  df-fv 4938  df-riota 5496  df-ov 5543  df-oprab 5544  df-mpt2 5545  df-sub 7247
This theorem is referenced by:  sub32  7308  nnncan  7309  pnpcan  7313  addsub4  7317  subsub4d  7416  2shfti  9660  nn0seqcvgd  10263
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