g.e. = lim{{[1+1/(2n)]^(2n)}^(-2)}*[1+1/(2n)] = [e^(-2)]*1 = e^(-2)
n→∞lim(1+1/2n)¹⁻⁴ⁿ=n→∞lim{[(1+1/2n)²ⁿ]⁻²}(1+1/2n)=n→∞lim{[(1+1/2n)²ⁿ]⁻²}[n→∞lim(1+1/2n)]=e⁻²
将1-4n分解成1和-2*(2n)则结果为e^(-2)
