For each positive integer n, let yₙ = [1/n(n+1)(n+2)…(n+n)]^(1/n) For x ∈ R, let [x] be the greatest integer less than or equal to x. If lim_(n→∞) yₙ = L, then the value of [L] is ______.
yn=[nn1(n+1)(n+2)⋯(n+n)]1/n
[x]=greatest integer≤x
To find: [L],L=limn→∞yn
nn(n+1)(n+2)⋯(n+n)=∏k=1n(1+nk)
yn=[∏k=1n(1+nk)]1/n
lnyn=n1∑k=1nln(1+nk)
limn→∞lnyn=∫01ln(1+x)dx
∫ln(1+x)dx=(1+x)ln(1+x)−(1+x)
∫01=(2ln2−2)−(0−1)=2ln2−1
lnL=2ln2−1=lne4
L=e4≈1.47
[L]=1