Description: The ratio of two positive numbers is positive. (Contributed by NM, 16-May-1999)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | ltplus1.1 | |- A e. RR | |
| prodgt0.2 | |- B e. RR | ||
| Assertion | divgt0i | |- ( ( 0 < A /\ 0 < B ) -> 0 < ( A / B ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | ltplus1.1 | |- A e. RR | |
| 2 | prodgt0.2 | |- B e. RR | |
| 3 | divgt0 | |- ( ( ( A e. RR /\ 0 < A ) /\ ( B e. RR /\ 0 < B ) ) -> 0 < ( A / B ) ) | |
| 4 | 2 3 | mpanr1 | |- ( ( ( A e. RR /\ 0 < A ) /\ 0 < B ) -> 0 < ( A / B ) ) | 
| 5 | 1 4 | mpanl1 | |- ( ( 0 < A /\ 0 < B ) -> 0 < ( A / B ) ) |