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theorem proved term proof

phi_inv_eq

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formal statement (Lean)

 256theorem phi_inv_eq : goldenRatio⁻¹ = goldenRatio - 1 := by

proof body

Term-mode proof.

 257  -- φ⁻¹ = -ψ = -(1 - √5)/2 = (√5 - 1)/2 = (1 + √5)/2 - 1 = φ - 1
 258  rw [inv_goldenRatio]
 259  unfold goldenRatio goldenConj
 260  ring
 261

used by (6)

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depends on (2)

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