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Mirrors > Home > MPE Home > Th. List > fac2 | Structured version Visualization version GIF version |
Description: The factorial of 2. (Contributed by NM, 17-Mar-2005.) |
Ref | Expression |
---|---|
fac2 | ⊢ (!‘2) = 2 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-2 11701 | . . 3 ⊢ 2 = (1 + 1) | |
2 | 1 | fveq2i 6673 | . 2 ⊢ (!‘2) = (!‘(1 + 1)) |
3 | 1nn0 11914 | . . . 4 ⊢ 1 ∈ ℕ0 | |
4 | facp1 13639 | . . . 4 ⊢ (1 ∈ ℕ0 → (!‘(1 + 1)) = ((!‘1) · (1 + 1))) | |
5 | 3, 4 | ax-mp 5 | . . 3 ⊢ (!‘(1 + 1)) = ((!‘1) · (1 + 1)) |
6 | fac1 13638 | . . . . 5 ⊢ (!‘1) = 1 | |
7 | 1p1e2 11763 | . . . . 5 ⊢ (1 + 1) = 2 | |
8 | 6, 7 | oveq12i 7168 | . . . 4 ⊢ ((!‘1) · (1 + 1)) = (1 · 2) |
9 | 2cn 11713 | . . . . 5 ⊢ 2 ∈ ℂ | |
10 | 9 | mulid2i 10646 | . . . 4 ⊢ (1 · 2) = 2 |
11 | 8, 10 | eqtri 2844 | . . 3 ⊢ ((!‘1) · (1 + 1)) = 2 |
12 | 5, 11 | eqtri 2844 | . 2 ⊢ (!‘(1 + 1)) = 2 |
13 | 2, 12 | eqtri 2844 | 1 ⊢ (!‘2) = 2 |
Colors of variables: wff setvar class |
Syntax hints: = wceq 1537 ∈ wcel 2114 ‘cfv 6355 (class class class)co 7156 1c1 10538 + caddc 10540 · cmul 10542 2c2 11693 ℕ0cn0 11898 !cfa 13634 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2161 ax-12 2177 ax-ext 2793 ax-sep 5203 ax-nul 5210 ax-pow 5266 ax-pr 5330 ax-un 7461 ax-cnex 10593 ax-resscn 10594 ax-1cn 10595 ax-icn 10596 ax-addcl 10597 ax-addrcl 10598 ax-mulcl 10599 ax-mulrcl 10600 ax-mulcom 10601 ax-addass 10602 ax-mulass 10603 ax-distr 10604 ax-i2m1 10605 ax-1ne0 10606 ax-1rid 10607 ax-rnegex 10608 ax-rrecex 10609 ax-cnre 10610 ax-pre-lttri 10611 ax-pre-lttrn 10612 ax-pre-ltadd 10613 ax-pre-mulgt0 10614 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-mo 2622 df-eu 2654 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-nel 3124 df-ral 3143 df-rex 3144 df-reu 3145 df-rab 3147 df-v 3496 df-sbc 3773 df-csb 3884 df-dif 3939 df-un 3941 df-in 3943 df-ss 3952 df-pss 3954 df-nul 4292 df-if 4468 df-pw 4541 df-sn 4568 df-pr 4570 df-tp 4572 df-op 4574 df-uni 4839 df-iun 4921 df-br 5067 df-opab 5129 df-mpt 5147 df-tr 5173 df-id 5460 df-eprel 5465 df-po 5474 df-so 5475 df-fr 5514 df-we 5516 df-xp 5561 df-rel 5562 df-cnv 5563 df-co 5564 df-dm 5565 df-rn 5566 df-res 5567 df-ima 5568 df-pred 6148 df-ord 6194 df-on 6195 df-lim 6196 df-suc 6197 df-iota 6314 df-fun 6357 df-fn 6358 df-f 6359 df-f1 6360 df-fo 6361 df-f1o 6362 df-fv 6363 df-riota 7114 df-ov 7159 df-oprab 7160 df-mpo 7161 df-om 7581 df-2nd 7690 df-wrecs 7947 df-recs 8008 df-rdg 8046 df-er 8289 df-en 8510 df-dom 8511 df-sdom 8512 df-pnf 10677 df-mnf 10678 df-xr 10679 df-ltxr 10680 df-le 10681 df-sub 10872 df-neg 10873 df-nn 11639 df-2 11701 df-n0 11899 df-z 11983 df-uz 12245 df-seq 13371 df-fac 13635 |
This theorem is referenced by: fac3 13641 bcn2 13680 4bc2eq6 13690 ef4p 15466 efgt1p2 15467 symg2hash 18520 dveflem 24576 poimirlem9 34916 wallispi2lem2 42377 |
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