记y=(1+2∧n+3∧n+4∧n)∧ 1/n
lny=1/n ln(1+2∧n+3∧n+4∧n)
=1/n* {nln4+ln[1/4^n+(2/4)^n+(3/4)^n+1]}
=ln4+1/n *ln[1/4^n+(2/4)^n+(3/4)^n+1]
n->无穷时,lny=ln4
得：y=4
原式=4 记y=(1+2∧n+3∧n+4∧n)∧ 1/n
lny=1/n ln(1+2∧n+3∧n+4∧n)
=1/n* {nln4+ln[1/4^n+(2/4)^n+(3/4)^n+1]}
=ln4+1/n *ln[1/4^n+(2/4)^n+(3/4)^n+1]
n->无穷时,lny=ln4
得：y=4
原式=4