| Step |
Hyp |
Ref |
Expression |
| 1 |
|
2zrng.e |
|
| 2 |
|
2zrngbas.r |
|
| 3 |
1 2
|
2zrngamgm |
|
| 4 |
|
elrabi |
|
| 5 |
|
elrabi |
|
| 6 |
|
elrabi |
|
| 7 |
4 5 6
|
3anim123i |
|
| 8 |
|
zcn |
|
| 9 |
|
zcn |
|
| 10 |
|
zcn |
|
| 11 |
8 9 10
|
3anim123i |
|
| 12 |
|
addass |
|
| 13 |
7 11 12
|
3syl |
|
| 14 |
13
|
rgen3 |
|
| 15 |
1 2
|
2zrngbas |
|
| 16 |
1 15
|
eqtr3i |
|
| 17 |
1 2
|
2zrngadd |
|
| 18 |
16 17
|
issgrp |
|
| 19 |
3 14 18
|
mpbir2an |
|