Description: Deduction form of logne0 . See logccne0d for a more general version. (Contributed by SN, 25-Apr-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | logne0d.a | |- ( ph -> A e. RR+ ) | |
| logne0d.1 | |- ( ph -> A =/= 1 ) | ||
| Assertion | logne0d | |- ( ph -> ( log ` A ) =/= 0 ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | logne0d.a | |- ( ph -> A e. RR+ ) | |
| 2 | logne0d.1 | |- ( ph -> A =/= 1 ) | |
| 3 | logne0 | |- ( ( A e. RR+ /\ A =/= 1 ) -> ( log ` A ) =/= 0 ) | |
| 4 | 1 2 3 | syl2anc | |- ( ph -> ( log ` A ) =/= 0 ) |