theorem
proved
tactic proof
phi_pow_51_in_interval
show as:
view Lean formalization →
formal statement (Lean)
127theorem phi_pow_51_in_interval :
128 phi_pow_51_interval.contains (((1 + Real.sqrt 5) / 2) ^ (51 : ℝ)) := by
proof body
Tactic-mode proof.
129 simp only [Interval.contains, phi_pow_51_interval]
130 -- (1 + √5)/2 = goldenRatio
131 have h_phi : (1 + Real.sqrt 5) / 2 = goldenRatio := rfl
132 -- Convert real power to natural power: x^(51 : ℝ) = x^51
133 have h_eq : ((1 + Real.sqrt 5) / 2) ^ (51 : ℝ) = goldenRatio ^ (51 : ℕ) := by
134 conv_lhs => rw [h_phi]
135 exact Real.rpow_natCast goldenRatio 51
136 rw [h_eq]
137 have h := phi_pow51_in_interval_proven
138 simp only [Interval.contains, phi_pow51_interval_proven] at h
139 exact h
140
141/-- φ^8 interval ≈ 46.979 - PROVEN -/