∵正数的等比数列{a n}满足a 1a 7=4,∴
a 24 =4,可得a 4=2,
∵a 6=8,
∴
a 6
a 4 =q 2,可得q 2=4,可得q=2,∴a 1×q 3=2,得a 1=
1
4 ,
∴a n=a 1×q n=
1
4 ×2 n-1=2 n-3,
∴f(x)=a 1x+a 2x 2+a 3x 3+…+a 10x 10,
∴f(
1
2 )=a 1
1
2 +a 2
1
2 2+a 3(
1
2 ) 3+…+a 10(
1
2 ) 10=
1
2 3 +
1
2 3 +…+
1
2 3 =10×
1
2 3 =
10
8 =
5
4 ,
故答案为
5
4 ;