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阅读下列材料:关于x的方程x2-3x+1=0(x≠0)方程两边同时乘以1x得:x-3+1x=0即x+1x=3(x+1x)2=x2+1x2

题目详情
阅读下列材料:关于x的方程x2-3x+1=0(x≠0)
方程两边同时乘以
1
x
得:x-3+
1
x
=0即x+
1
x
=3
(x+
1
x
2=x2+
1
x2
+2•x•
1
x
=x2+
1
x2
+2
x2+
1
x2
=(x+
1
x
2-2=32-2=7
根据以上材料,解答下列问题:
(1)x2-4x+1=0(x≠0),则x2+
1
x2
=___,x4+
1
x4
=___
(2)2x2-7x+2=0(x≠0),求x3+
1
x3
的值.
▼优质解答
答案和解析
(1)方程两边同时乘以
1
x
得:x-4+
1
x
=0,则x+
1
x
=4,
两边平方得x2+
1
x2
+2=16,则x2+
1
x2
=14,
两边平方得x4+
1
x4
+2=196,则x4+
1
x4
=194.
故答案是:14,194;
(2)方程两边同时除以2x得x-
7
2
+
1
x
=0,
则x+
1
x
=
7
2

两边平方得x2+
1
x2
+2=
49
4
,则x2+
1
x2
=
41
4

x3+
1
x3
=(x+
1
x
)(x2+
1
x2
-1)=
7
2
×(
41
4
-1)=
7
2
×
37
4
=
259
8