Question

在(

x

2

-

1

3 x

)8的展開式中常數項是______．

Answer 1

二項展開式的通項為Tr+1=(-1)r(

1

2

)8-r

C

r8

x8-

4r

3

令8-

4r

3

=0
解得r=6
∴展開式的常數項為(

1

2

)2

C

68

=7
故答案為：7