2√(2/3)=√(4×2/3)=√[2+(2/3)]=√[2+2/(2²-1)]
3√(3/8)=√(9×3/8)=√[3+(3/8)]=√[3+3/(3²-1)]
4√(4/15)=√(16×4/15)=√[4+(4/15)]=√[4+4/(4²-1)]
……
n√[n/(n²-1)]=√[n²×n/(n²-1)]
=√{[n(n²-1)+n]/(n²-1)}
=√[n(n²-1)/(n²-1)+n/(n²-1)]
=√[n+n/(n²-1)]
规律是:
n√[n/(n²-1)]=√[n+n/(n²-1)] (n≥2,n为自然数)