收益 F(p) = Q(p)*p = (12-p/2)*pF(6) = 48p=6时增加1%，就是 p = (1+1%)*6 = 6.06F(6.06) = (12-3.03)*6.06 = 54.36收益增加 F(6.06) -F(6) = 6.36增加百分比 =【F(6.06) -F(6)】/F(6) = 13.25%
