Question

若

lim

n→∞

22n-1-a•3n+1

3n+1+a•22n

=1，则a=______．

Answer 1

∵

lim

n→∞

22n-1-a•3n+1

3n+1+a•22n

=

lim

n→∞

1 2 -3a•( 3 4 )n

3•( 3 4 )n+a

=

1

2a

∴

1

2a

=1∴a=

1

2

故答案为：

1

2