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Description: A counterexample to FLT with A , C coprime also has A , B coprime. Converse of fltaccoprm . (Contributed by SN, 22-Aug-2024)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | fltabcoprm.a | |- ( ph -> A e. NN ) |
|
| fltabcoprm.b | |- ( ph -> B e. NN ) |
||
| fltabcoprm.c | |- ( ph -> C e. NN ) |
||
| fltabcoprm.2 | |- ( ph -> ( A gcd C ) = 1 ) |
||
| fltabcoprm.3 | |- ( ph -> ( ( A ^ 2 ) + ( B ^ 2 ) ) = ( C ^ 2 ) ) |
||
| Assertion | fltabcoprm | |- ( ph -> ( A gcd B ) = 1 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | fltabcoprm.a | |- ( ph -> A e. NN ) |
|
| 2 | fltabcoprm.b | |- ( ph -> B e. NN ) |
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| 3 | fltabcoprm.c | |- ( ph -> C e. NN ) |
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| 4 | fltabcoprm.2 | |- ( ph -> ( A gcd C ) = 1 ) |
|
| 5 | fltabcoprm.3 | |- ( ph -> ( ( A ^ 2 ) + ( B ^ 2 ) ) = ( C ^ 2 ) ) |
|
| 6 | coprmgcdb | |- ( ( A e. NN /\ C e. NN ) -> ( A. i e. NN ( ( i || A /\ i || C ) -> i = 1 ) <-> ( A gcd C ) = 1 ) ) |
|
| 7 | 1 3 6 | syl2anc | |- ( ph -> ( A. i e. NN ( ( i || A /\ i || C ) -> i = 1 ) <-> ( A gcd C ) = 1 ) ) |
| 8 | 4 7 | mpbird | |- ( ph -> A. i e. NN ( ( i || A /\ i || C ) -> i = 1 ) ) |
| 9 | simprl | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> i || A ) |
|
| 10 | simplr | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> i e. NN ) |
|
| 11 | 10 | nnsqcld | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( i ^ 2 ) e. NN ) |
| 12 | 11 | nnzd | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( i ^ 2 ) e. ZZ ) |
| 13 | 1 | ad2antrr | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> A e. NN ) |
| 14 | 13 | nnsqcld | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( A ^ 2 ) e. NN ) |
| 15 | 14 | nnzd | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( A ^ 2 ) e. ZZ ) |
| 16 | 2 | ad2antrr | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> B e. NN ) |
| 17 | 16 | nnsqcld | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( B ^ 2 ) e. NN ) |
| 18 | 17 | nnzd | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( B ^ 2 ) e. ZZ ) |
| 19 | dvdssqlem | |- ( ( i e. NN /\ A e. NN ) -> ( i || A <-> ( i ^ 2 ) || ( A ^ 2 ) ) ) |
|
| 20 | 10 13 19 | syl2anc | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( i || A <-> ( i ^ 2 ) || ( A ^ 2 ) ) ) |
| 21 | 9 20 | mpbid | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( i ^ 2 ) || ( A ^ 2 ) ) |
| 22 | simprr | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> i || B ) |
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| 23 | dvdssqlem | |- ( ( i e. NN /\ B e. NN ) -> ( i || B <-> ( i ^ 2 ) || ( B ^ 2 ) ) ) |
|
| 24 | 10 16 23 | syl2anc | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( i || B <-> ( i ^ 2 ) || ( B ^ 2 ) ) ) |
| 25 | 22 24 | mpbid | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( i ^ 2 ) || ( B ^ 2 ) ) |
| 26 | 12 15 18 21 25 | dvds2addd | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( i ^ 2 ) || ( ( A ^ 2 ) + ( B ^ 2 ) ) ) |
| 27 | 5 | ad2antrr | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( ( A ^ 2 ) + ( B ^ 2 ) ) = ( C ^ 2 ) ) |
| 28 | 26 27 | breqtrd | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( i ^ 2 ) || ( C ^ 2 ) ) |
| 29 | 3 | ad2antrr | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> C e. NN ) |
| 30 | dvdssqlem | |- ( ( i e. NN /\ C e. NN ) -> ( i || C <-> ( i ^ 2 ) || ( C ^ 2 ) ) ) |
|
| 31 | 10 29 30 | syl2anc | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( i || C <-> ( i ^ 2 ) || ( C ^ 2 ) ) ) |
| 32 | 28 31 | mpbird | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> i || C ) |
| 33 | 9 32 | jca | |- ( ( ( ph /\ i e. NN ) /\ ( i || A /\ i || B ) ) -> ( i || A /\ i || C ) ) |
| 34 | 33 | ex | |- ( ( ph /\ i e. NN ) -> ( ( i || A /\ i || B ) -> ( i || A /\ i || C ) ) ) |
| 35 | 34 | imim1d | |- ( ( ph /\ i e. NN ) -> ( ( ( i || A /\ i || C ) -> i = 1 ) -> ( ( i || A /\ i || B ) -> i = 1 ) ) ) |
| 36 | 35 | ralimdva | |- ( ph -> ( A. i e. NN ( ( i || A /\ i || C ) -> i = 1 ) -> A. i e. NN ( ( i || A /\ i || B ) -> i = 1 ) ) ) |
| 37 | 8 36 | mpd | |- ( ph -> A. i e. NN ( ( i || A /\ i || B ) -> i = 1 ) ) |
| 38 | coprmgcdb | |- ( ( A e. NN /\ B e. NN ) -> ( A. i e. NN ( ( i || A /\ i || B ) -> i = 1 ) <-> ( A gcd B ) = 1 ) ) |
|
| 39 | 1 2 38 | syl2anc | |- ( ph -> ( A. i e. NN ( ( i || A /\ i || B ) -> i = 1 ) <-> ( A gcd B ) = 1 ) ) |
| 40 | 37 39 | mpbid | |- ( ph -> ( A gcd B ) = 1 ) |