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))^(x/2)=Lim[(1+(1/х))^(x/1)]^((1/x)*(x/2))=Lim[(1+(1/х))^(x/1)]^(1/2)=e^(1/2)