问题
解答题
已知x2-3x+1=0,求(1)x+
|
答案
(1)∵x2-3x+1=0,
∴x≠0,
方程两边同时除以x,
得x-3+
=0,1 x
∴x+
=3;1 x
(2)∵x+
=3,1 x
∴(x+
)2=9,(x+1 x
)3=27,1 x
即x2+2+
=9,x3+3x+1 x2
+3 x
=27,1 x3
∴x2+
=7,x3+1 x2
=18,1 x3
∴(x2+
)(x3+1 x2
)=7×18,1 x3
∴x5+
+x+1 x5
=126,1 x
∴x5+
=123.1 x5