Description: Closure of subtraction of rationals. (Contributed by NM, 2-Aug-2004)
Ref | Expression | ||
---|---|---|---|
Assertion | qsubcl | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | qcn | |
|
2 | qcn | |
|
3 | negsub | |
|
4 | 1 2 3 | syl2an | |
5 | qnegcl | |
|
6 | qaddcl | |
|
7 | 5 6 | sylan2 | |
8 | 4 7 | eqeltrrd | |