Description: The exponential of a real number is a positive real. (Contributed by Mario Carneiro, 10-Nov-2013)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | rpefcl | ⊢ ( 𝐴 ∈ ℝ → ( exp ‘ 𝐴 ) ∈ ℝ+ ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | reefcl | ⊢ ( 𝐴 ∈ ℝ → ( exp ‘ 𝐴 ) ∈ ℝ ) | |
| 2 | efgt0 | ⊢ ( 𝐴 ∈ ℝ → 0 < ( exp ‘ 𝐴 ) ) | |
| 3 | 1 2 | elrpd | ⊢ ( 𝐴 ∈ ℝ → ( exp ‘ 𝐴 ) ∈ ℝ+ ) |