Step |
Hyp |
Ref |
Expression |
1 |
|
nncn |
|- ( A e. NN -> A e. CC ) |
2 |
1
|
3ad2ant2 |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> A e. CC ) |
3 |
2
|
sqcld |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( A ^ 2 ) e. CC ) |
4 |
|
nncn |
|- ( D e. NN -> D e. CC ) |
5 |
4
|
3ad2ant1 |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> D e. CC ) |
6 |
|
nncn |
|- ( B e. NN -> B e. CC ) |
7 |
6
|
3ad2ant3 |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> B e. CC ) |
8 |
7
|
sqcld |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( B ^ 2 ) e. CC ) |
9 |
5 8
|
mulcld |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( D x. ( B ^ 2 ) ) e. CC ) |
10 |
3 9
|
subeq0ad |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( ( ( A ^ 2 ) - ( D x. ( B ^ 2 ) ) ) = 0 <-> ( A ^ 2 ) = ( D x. ( B ^ 2 ) ) ) ) |
11 |
|
nnne0 |
|- ( B e. NN -> B =/= 0 ) |
12 |
11
|
3ad2ant3 |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> B =/= 0 ) |
13 |
|
sqne0 |
|- ( B e. CC -> ( ( B ^ 2 ) =/= 0 <-> B =/= 0 ) ) |
14 |
7 13
|
syl |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( ( B ^ 2 ) =/= 0 <-> B =/= 0 ) ) |
15 |
12 14
|
mpbird |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( B ^ 2 ) =/= 0 ) |
16 |
3 5 8 15
|
divmul3d |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( ( ( A ^ 2 ) / ( B ^ 2 ) ) = D <-> ( A ^ 2 ) = ( D x. ( B ^ 2 ) ) ) ) |
17 |
|
sqdiv |
|- ( ( A e. CC /\ B e. CC /\ B =/= 0 ) -> ( ( A / B ) ^ 2 ) = ( ( A ^ 2 ) / ( B ^ 2 ) ) ) |
18 |
17
|
fveq2d |
|- ( ( A e. CC /\ B e. CC /\ B =/= 0 ) -> ( sqrt ` ( ( A / B ) ^ 2 ) ) = ( sqrt ` ( ( A ^ 2 ) / ( B ^ 2 ) ) ) ) |
19 |
2 7 12 18
|
syl3anc |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( sqrt ` ( ( A / B ) ^ 2 ) ) = ( sqrt ` ( ( A ^ 2 ) / ( B ^ 2 ) ) ) ) |
20 |
|
nnre |
|- ( A e. NN -> A e. RR ) |
21 |
20
|
3ad2ant2 |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> A e. RR ) |
22 |
|
nnre |
|- ( B e. NN -> B e. RR ) |
23 |
22
|
3ad2ant3 |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> B e. RR ) |
24 |
21 23 12
|
redivcld |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( A / B ) e. RR ) |
25 |
|
nnnn0 |
|- ( A e. NN -> A e. NN0 ) |
26 |
25
|
nn0ge0d |
|- ( A e. NN -> 0 <_ A ) |
27 |
26
|
3ad2ant2 |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> 0 <_ A ) |
28 |
|
nngt0 |
|- ( B e. NN -> 0 < B ) |
29 |
28
|
3ad2ant3 |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> 0 < B ) |
30 |
|
divge0 |
|- ( ( ( A e. RR /\ 0 <_ A ) /\ ( B e. RR /\ 0 < B ) ) -> 0 <_ ( A / B ) ) |
31 |
21 27 23 29 30
|
syl22anc |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> 0 <_ ( A / B ) ) |
32 |
24 31
|
sqrtsqd |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( sqrt ` ( ( A / B ) ^ 2 ) ) = ( A / B ) ) |
33 |
19 32
|
eqtr3d |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( sqrt ` ( ( A ^ 2 ) / ( B ^ 2 ) ) ) = ( A / B ) ) |
34 |
|
nnq |
|- ( A e. NN -> A e. QQ ) |
35 |
34
|
3ad2ant2 |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> A e. QQ ) |
36 |
|
nnq |
|- ( B e. NN -> B e. QQ ) |
37 |
36
|
3ad2ant3 |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> B e. QQ ) |
38 |
|
qdivcl |
|- ( ( A e. QQ /\ B e. QQ /\ B =/= 0 ) -> ( A / B ) e. QQ ) |
39 |
35 37 12 38
|
syl3anc |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( A / B ) e. QQ ) |
40 |
33 39
|
eqeltrd |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( sqrt ` ( ( A ^ 2 ) / ( B ^ 2 ) ) ) e. QQ ) |
41 |
|
fveq2 |
|- ( ( ( A ^ 2 ) / ( B ^ 2 ) ) = D -> ( sqrt ` ( ( A ^ 2 ) / ( B ^ 2 ) ) ) = ( sqrt ` D ) ) |
42 |
41
|
eleq1d |
|- ( ( ( A ^ 2 ) / ( B ^ 2 ) ) = D -> ( ( sqrt ` ( ( A ^ 2 ) / ( B ^ 2 ) ) ) e. QQ <-> ( sqrt ` D ) e. QQ ) ) |
43 |
40 42
|
syl5ibcom |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( ( ( A ^ 2 ) / ( B ^ 2 ) ) = D -> ( sqrt ` D ) e. QQ ) ) |
44 |
16 43
|
sylbird |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( ( A ^ 2 ) = ( D x. ( B ^ 2 ) ) -> ( sqrt ` D ) e. QQ ) ) |
45 |
10 44
|
sylbid |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( ( ( A ^ 2 ) - ( D x. ( B ^ 2 ) ) ) = 0 -> ( sqrt ` D ) e. QQ ) ) |
46 |
45
|
necon3bd |
|- ( ( D e. NN /\ A e. NN /\ B e. NN ) -> ( -. ( sqrt ` D ) e. QQ -> ( ( A ^ 2 ) - ( D x. ( B ^ 2 ) ) ) =/= 0 ) ) |
47 |
46
|
imp |
|- ( ( ( D e. NN /\ A e. NN /\ B e. NN ) /\ -. ( sqrt ` D ) e. QQ ) -> ( ( A ^ 2 ) - ( D x. ( B ^ 2 ) ) ) =/= 0 ) |