说明：此题n为大于等于的整数也是成立的证明：（1）当n=1时,∵4n/(n+1)=4*1/(1+1)=2(2n)!/(n!)^2=(2*1)!/(1!)^2=2∴4n/(n+1)≤(2n)!/(n!)^2成立当n=2时,∵4n/(n+1)=4*2/(2+1)=8/3(2n)!/(n!)^2=(2*2)!/(2!)^2=6∴4n/(...