Description: Closure law for exponentiation of positive reals. (Contributed by Mario Carneiro, 28-May-2016)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | rpexpcld.1 | |- ( ph -> A e. RR+ ) | |
| rpexpcld.2 | |- ( ph -> N e. ZZ ) | ||
| Assertion | rpexpcld | |- ( ph -> ( A ^ N ) e. RR+ ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | rpexpcld.1 | |- ( ph -> A e. RR+ ) | |
| 2 | rpexpcld.2 | |- ( ph -> N e. ZZ ) | |
| 3 | rpexpcl | |- ( ( A e. RR+ /\ N e. ZZ ) -> ( A ^ N ) e. RR+ ) | |
| 4 | 1 2 3 | syl2anc | |- ( ph -> ( A ^ N ) e. RR+ ) |