【Terry Tung】評論
dTR/dP = Q(1-E) , 薄利多銷= P下降時, TR上升 = dTR/dP < 0 = E1
dTR/dP = Q(1-E) , 薄利多銷=> P下降時, TR上升 => dTR/dP < 0 => E>1