假设a=(2/π arctan X)^X
lna=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^2+1)= -2/π *1=-2/π
lim a= e^(-2/π)
假设a=(2/π arctan X)^X
lna=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^2+1)= -2/π *1=-2/π
lim a= e^(-2/π)