theorem lafferRevenue_symmetric {B₀ η ε : ℝ} (hη : η ≠ 0) :
lafferRevenue B₀ η (lafferPeak η - ε) =
lafferRevenue B₀ η (lafferPeak η + ε) := by
simp only [lafferRevenue, lafferPeak]
field_simp
ringGrowth and Dynamic Tax Revenue (Layer 4-5 of Macro Extension)