求lim n趋于无穷大((n+1)(n+2)(n+3)) / 5n的三次方 的极限

问题描述:

求lim n趋于无穷大((n+1)(n+2)(n+3)) / 5n的三次方 的极限

=lim(1+1/n)(1+2/n)(1+3/n)/5
=1*1*1/5
=1/5

上下除以n³
原式=lim(1+1/n)(1+2/n)(1+3/n)/5
=1*1*1/5
=1/5

limn->∞[(n+1)(n+2)(n+3)]/5n^3
=limn->∞n^3[(1+1/n)(1+2/n)(1+3/n)]/5n^3
=(1+0)(1+0)(1+0)/5
=1/5