theorem
proved
tactic proof
J_phi_pos
show as:
view Lean formalization →
formal statement (Lean)
41theorem J_phi_pos : J phi > 0 := by
proof body
Tactic-mode proof.
42 unfold J
43 have h_phi_sq : phi ^ 2 = phi + 1 := Constants.phi_sq_eq
44 have h_phi_pos : 0 < phi := Constants.phi_pos
45 have h_phi_inv : phi⁻¹ = phi - 1 := by
46 have h : phi * (phi - 1) = 1 := by nlinarith [h_phi_sq]
47 field_simp; linarith
48 rw [h_phi_inv]
49 linarith [Constants.phi_gt_onePointFive]
50