Theorem 2p2e4 9119

Description: Two plus two equals four. For more information, see "2+2=4 Trivia" on the Metamath Proof Explorer Home Page: https://us.metamath.org/mpeuni/mmset.html#trivia. (Contributed by NM, 27-May-1999.)

Assertion

Ref	Expression
2p2e4	⊢ (2 + 2) = 4

Proof of Theorem 2p2e4

Step	Hyp	Ref	Expression
1		df-2 9051	. . 3 ⊢ 2 = (1 + 1)
2	1	oveq2i 5934	. 2 ⊢ (2 + 2) = (2 + (1 + 1))
3		df-4 9053	. . 3 ⊢ 4 = (3 + 1)
4		df-3 9052	. . . 4 ⊢ 3 = (2 + 1)
5	4	oveq1i 5933	. . 3 ⊢ (3 + 1) = ((2 + 1) + 1)
6		2cn 9063	. . . 4 ⊢ 2 ∈ ℂ
7		ax-1cn 7974	. . . 4 ⊢ 1 ∈ ℂ
8	6, 7, 7	addassi 8036	. . 3 ⊢ ((2 + 1) + 1) = (2 + (1 + 1))
9	3, 5, 8	3eqtri 2221	. 2 ⊢ 4 = (2 + (1 + 1))
10	2, 9	eqtr4i 2220	1 ⊢ (2 + 2) = 4

Syntax hints:   = wceq 1364  (class class class)co 5923  1c1 7882   + caddc 7884  2c2 9043  3c3 9044  4c4 9045

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-ext 2178  ax-resscn 7973  ax-1cn 7974  ax-1re 7975  ax-addrcl 7978  ax-addass 7983

This theorem depends on definitions:  df-bi 117  df-3an 982  df-tru 1367  df-nf 1475  df-sb 1777  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-rex 2481  df-v 2765  df-un 3161  df-in 3163  df-ss 3170  df-sn 3629  df-pr 3630  df-op 3632  df-uni 3841  df-br 4035  df-iota 5220  df-fv 5267  df-ov 5926  df-2 9051  df-3 9052  df-4 9053

This theorem is referenced by:  2t2e4  9147  i4  10736  4bc2eq6  10868  resqrexlemover  11177  resqrexlemcalc1  11181  ef01bndlem  11923  6gcd4e2  12172  pythagtriplem1  12444