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已知x+1x=2,求代数式x+x2+x4+x8+…+x1024+1x+1x2+1x4+1x8+…+1x1024.

题目详情
已知x+
1
x
=2,求代数式x+x2+x4+x8+…+x1024+
1
x
+
1
x2
+
1
x4
+
1
x8
+…+
1
x1024
▼优质解答
答案和解析
∵x+
1
x
=2,
x2+
1
x2
=(x+
1
x
)2-2=22-2=2,
x4+
1
x4
=(x2+
1
x2
)2-2=22-2=2,
∴x+x2+x4+x8+…+x1024+
1
x
+
1
x2
+
1
x4
+
1
x8
+…+
1
x1024

=(x+
1
x
)+(x2+
1
x2
)+…+(x1024+
1
x1024
)
=
2+2+2+…+2
11个2

=2×11
=22.