Axiom ax-pre-mulgt0 7946

Description: The product of two positive reals is positive. Axiom for real and complex numbers, justified by Theorem axpre-mulgt0 7904. (Contributed by NM, 13-Oct-2005.)

Assertion

Ref	Expression
ax-pre-mulgt0	⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((0 <ℝ 𝐴 ∧ 0 <ℝ 𝐵) → 0 <ℝ (𝐴 · 𝐵)))

Detailed syntax breakdown of Axiom ax-pre-mulgt0

Step	Hyp	Ref	Expression
1		cA	. . . 4 class 𝐴
2		cr 7828	. . . 4 class ℝ
3	1, 2	wcel 2160	. . 3 wff 𝐴 ∈ ℝ
4		cB	. . . 4 class 𝐵
5	4, 2	wcel 2160	. . 3 wff 𝐵 ∈ ℝ
6	3, 5	wa 104	. 2 wff (𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ)
7		cc0 7829	. . . . 5 class 0
8		cltrr 7833	. . . . 5 class <ℝ
9	7, 1, 8	wbr 4018	. . . 4 wff 0 <ℝ 𝐴
10	7, 4, 8	wbr 4018	. . . 4 wff 0 <ℝ 𝐵
11	9, 10	wa 104	. . 3 wff (0 <ℝ 𝐴 ∧ 0 <ℝ 𝐵)
12		cmul 7834	. . . . 5 class ·
13	1, 4, 12	co 5891	. . . 4 class (𝐴 · 𝐵)
14	7, 13, 8	wbr 4018	. . 3 wff 0 <ℝ (𝐴 · 𝐵)
15	11, 14	wi 4	. 2 wff ((0 <ℝ 𝐴 ∧ 0 <ℝ 𝐵) → 0 <ℝ (𝐴 · 𝐵))
16	6, 15	wi 4	1 wff ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((0 <ℝ 𝐴 ∧ 0 <ℝ 𝐵) → 0 <ℝ (𝐴 · 𝐵)))

This axiom is referenced by:  axmulgt0  8047