假设a=(2/π arctan X)^Xlna=x*ln(2/π arctan X)lim lna=lim x*ln(2/π arctan X)=lim ln(2/π arctan X)/x^-1用络比达lim lna = 2/π/(x^2+1) /(2/π arctan X) /-x^-2=-x^2 /(arctan X * x^2+1)=-x^2 /(π/2 *(x^...