lim(1+2+3+...+n)/(1+3+5+...+2n-1)
=lim[n(n+1)/2]/[(1+2n-1)*n/2]
=lim(n+1)/2n
=lim(n/2n+1/2n)
=lim n→∞(1/2+1/2n)
=1/2