lim ((2n+1)/(2n+3))^(n/2)=Lim((2n+1+3-3)/(2n+3))^(n/2)=Lim(1-(2/(2n+3)))^(n/2)=Lim(1+(1/x))^(-(2x+3)/4)=Lim[(1+(1/х))^(x/1)]^((1/x)*(-(2х+3)/4))=Lim[(1+(1/х))^(x/1)]^(-(2х+3)/4х)=e^(-(2х+3)/4х)