题目内容
在数列{an}中,a1=2,an+1=an+ln(1+
),则an=( )
1 |
n |
A.2+lnn | B.2+(n-1)lnn | C.2+nlnn | D.1+n+lnn |
∵.a2=a1+ln(1+
),
a3=a2+ln(1+
),
…
∴an=an-1+ln(1+
)
a1+ln(
)(
)(
)…(
)=2+lnn
故选A
1 |
1 |
a3=a2+ln(1+
1 |
2 |
…
∴an=an-1+ln(1+
1 |
n-1 |
a1+ln(
2 |
1 |
3 |
2 |
4 |
3 |
n |
n-1 |
故选A
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