Step |
Hyp |
Ref |
Expression |
1 |
|
drgext.b |
|
2 |
|
drgext.1 |
|
3 |
|
drgext.2 |
|
4 |
|
drngring |
|
5 |
|
ringmnd |
|
6 |
2 4 5
|
3syl |
|
7 |
|
subrgsubg |
|
8 |
|
eqid |
|
9 |
8
|
subg0cl |
|
10 |
3 7 9
|
3syl |
|
11 |
|
eqid |
|
12 |
11
|
subrgss |
|
13 |
3 12
|
syl |
|
14 |
|
eqid |
|
15 |
14 11 8
|
ress0g |
|
16 |
6 10 13 15
|
syl3anc |
|
17 |
1 2 3
|
drgext0g |
|
18 |
1
|
a1i |
|
19 |
18 13
|
srasca |
|
20 |
19
|
fveq2d |
|
21 |
16 17 20
|
3eqtr3d |
|