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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 12036 | . . 3 ⊢ 2 = (1 + 1) | |
2 | 1 | fveq2i 6774 | . 2 ⊢ (!‘2) = (!‘(1 + 1)) |
3 | 1nn0 12249 | . . . 4 ⊢ 1 ∈ ℕ0 | |
4 | facp1 13990 | . . . 4 ⊢ (1 ∈ ℕ0 → (!‘(1 + 1)) = ((!‘1) · (1 + 1))) | |
5 | 3, 4 | ax-mp 5 | . . 3 ⊢ (!‘(1 + 1)) = ((!‘1) · (1 + 1)) |
6 | fac1 13989 | . . . . 5 ⊢ (!‘1) = 1 | |
7 | 1p1e2 12098 | . . . . 5 ⊢ (1 + 1) = 2 | |
8 | 6, 7 | oveq12i 7283 | . . . 4 ⊢ ((!‘1) · (1 + 1)) = (1 · 2) |
9 | 2cn 12048 | . . . . 5 ⊢ 2 ∈ ℂ | |
10 | 9 | mulid2i 10981 | . . . 4 ⊢ (1 · 2) = 2 |
11 | 8, 10 | eqtri 2768 | . . 3 ⊢ ((!‘1) · (1 + 1)) = 2 |
12 | 5, 11 | eqtri 2768 | . 2 ⊢ (!‘(1 + 1)) = 2 |
13 | 2, 12 | eqtri 2768 | 1 ⊢ (!‘2) = 2 |
Colors of variables: wff setvar class |
Syntax hints: = wceq 1542 ∈ wcel 2110 ‘cfv 6432 (class class class)co 7271 1c1 10873 + caddc 10875 · cmul 10877 2c2 12028 ℕ0cn0 12233 !cfa 13985 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1802 ax-4 1816 ax-5 1917 ax-6 1975 ax-7 2015 ax-8 2112 ax-9 2120 ax-10 2141 ax-11 2158 ax-12 2175 ax-ext 2711 ax-sep 5227 ax-nul 5234 ax-pow 5292 ax-pr 5356 ax-un 7582 ax-cnex 10928 ax-resscn 10929 ax-1cn 10930 ax-icn 10931 ax-addcl 10932 ax-addrcl 10933 ax-mulcl 10934 ax-mulrcl 10935 ax-mulcom 10936 ax-addass 10937 ax-mulass 10938 ax-distr 10939 ax-i2m1 10940 ax-1ne0 10941 ax-1rid 10942 ax-rnegex 10943 ax-rrecex 10944 ax-cnre 10945 ax-pre-lttri 10946 ax-pre-lttrn 10947 ax-pre-ltadd 10948 ax-pre-mulgt0 10949 |
This theorem depends on definitions: df-bi 206 df-an 397 df-or 845 df-3or 1087 df-3an 1088 df-tru 1545 df-fal 1555 df-ex 1787 df-nf 1791 df-sb 2072 df-mo 2542 df-eu 2571 df-clab 2718 df-cleq 2732 df-clel 2818 df-nfc 2891 df-ne 2946 df-nel 3052 df-ral 3071 df-rex 3072 df-reu 3073 df-rab 3075 df-v 3433 df-sbc 3721 df-csb 3838 df-dif 3895 df-un 3897 df-in 3899 df-ss 3909 df-pss 3911 df-nul 4263 df-if 4466 df-pw 4541 df-sn 4568 df-pr 4570 df-op 4574 df-uni 4846 df-iun 4932 df-br 5080 df-opab 5142 df-mpt 5163 df-tr 5197 df-id 5490 df-eprel 5496 df-po 5504 df-so 5505 df-fr 5545 df-we 5547 df-xp 5596 df-rel 5597 df-cnv 5598 df-co 5599 df-dm 5600 df-rn 5601 df-res 5602 df-ima 5603 df-pred 6201 df-ord 6268 df-on 6269 df-lim 6270 df-suc 6271 df-iota 6390 df-fun 6434 df-fn 6435 df-f 6436 df-f1 6437 df-fo 6438 df-f1o 6439 df-fv 6440 df-riota 7228 df-ov 7274 df-oprab 7275 df-mpo 7276 df-om 7707 df-2nd 7825 df-frecs 8088 df-wrecs 8119 df-recs 8193 df-rdg 8232 df-er 8481 df-en 8717 df-dom 8718 df-sdom 8719 df-pnf 11012 df-mnf 11013 df-xr 11014 df-ltxr 11015 df-le 11016 df-sub 11207 df-neg 11208 df-nn 11974 df-2 12036 df-n0 12234 df-z 12320 df-uz 12582 df-seq 13720 df-fac 13986 |
This theorem is referenced by: fac3 13992 bcn2 14031 4bc2eq6 14041 ef4p 15820 efgt1p2 15821 symg2hash 18997 dveflem 25141 poimirlem9 35782 wallispi2lem2 43584 |
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