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设a1,a2,…a10成等比数列,且a1a2…a10=32,记x=a1+a2+…+a10,y=1a1+1a2+…+1a10,则xy=.

题目详情
设a1,a2,…a10成等比数列,且a1a2…a10=32,记x=a1+a2+…+a10,y=
1
a1
+
1
a2
+…+
1
a10
,则
x
y
=______.
▼优质解答
答案和解析
∵a1,a2,…a10成等比数列,且a1a2…a10=32,
∴a1•a10=a2•a9=a3•a8=a4•a7=a5•a6=2
∴y=
1
a1
+
1
a2
+…+
1
a10

=
1
2
(
2
a1
+
2
a2
+…+
2
a10
)
=
1
2
(
a1a10
a1
+
a2a9
a2
+…+
a10a1
a10
)
=
1
2
(a1+a2+…+a10
=
1
2
x
x
y
=2
故答案为:2