已知f(x+1/x)=x^3+1/x^3,求f(x）的表达式
人气：252 ℃ 时间：2020-05-08 19:02:41
解答
令a=x+1/x
a²=x²+2+1/x²
x²+1/x²=a²-2
x³+1/x³=(x+1/x)(x²-1+1/x²)=a³-3a
f(a)=a²-3a
所以f(x)=x²-3x
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