Description: Addition of positive and nonnegative numbers is positive. (Contributed by Asger C. Ipsen, 12-May-2021)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | leidd.1 | |- ( ph -> A e. RR ) | |
| ltnegd.2 | |- ( ph -> B e. RR ) | ||
| addgtge0d.3 | |- ( ph -> 0 < A ) | ||
| addgtge0d.4 | |- ( ph -> 0 <_ B ) | ||
| Assertion | addgtge0d | |- ( ph -> 0 < ( A + B ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | leidd.1 | |- ( ph -> A e. RR ) | |
| 2 | ltnegd.2 | |- ( ph -> B e. RR ) | |
| 3 | addgtge0d.3 | |- ( ph -> 0 < A ) | |
| 4 | addgtge0d.4 | |- ( ph -> 0 <_ B ) | |
| 5 | addgtge0 | |- ( ( ( A e. RR /\ B e. RR ) /\ ( 0 < A /\ 0 <_ B ) ) -> 0 < ( A + B ) ) | |
| 6 | 1 2 3 4 5 | syl22anc | |- ( ph -> 0 < ( A + B ) ) |