Step |
Hyp |
Ref |
Expression |
1 |
|
subsubs4d.1 |
|
2 |
|
subsubs4d.2 |
|
3 |
|
subsubs4d.3 |
|
4 |
2
|
negscld |
|
5 |
3
|
negscld |
|
6 |
1 4 5
|
addsassd |
|
7 |
1 2
|
subsvald |
|
8 |
7
|
oveq1d |
|
9 |
1 4
|
addscld |
|
10 |
9 3
|
subsvald |
|
11 |
8 10
|
eqtrd |
|
12 |
2 3
|
addscld |
|
13 |
1 12
|
subsvald |
|
14 |
|
negsdi |
|
15 |
2 3 14
|
syl2anc |
|
16 |
15
|
oveq2d |
|
17 |
13 16
|
eqtrd |
|
18 |
6 11 17
|
3eqtr4d |
|