已知x2-3x+1=0,求x3+1⼀x3的值 (过程要详细)

2024-12-28 09:16:26
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回答1:

解答:
x²-3x+1=0
∵ x≠0,两边同时除以x
x-3+1/x=0
x+1/x=3
(x+1/x)²=9
x²+1/x²+2=9
∴ x²+1/x²=7
∴ x³+1/x³
=(x+1/x)(x²-1+1/x²)
=3*(7-1)
=18