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已知：x+1/x=4,求下列各式的值：（1）x^2+1/x^2,(2)x^3+1/x^3.
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已知：x+1/x=4,求下列各式的值：（1）x^2+1/x^2,(2)x^3+1/x^3.
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答案和解析
已知：x+1/x=4,求下列各式的值：
（1）x^2+1/x^2,
=(x+1/x)²-2
=4²-2
=16-2
=14;
(2)x^3+1/x^3.
=(x+1/x)(x²-1+1/x²)
=4×((x+1/x)²-3)
=4×(16-3)
=4×13
=52;
很高兴为您解答,skyhunter002为您答疑解惑
如果本题有什么不明白可以追问,
（1）x^2+1/x^2,
=(x+1/x)²-2
=4²-2
=16-2
=14;
(2)x^3+1/x^3.
=(x+1/x)(x²-1+1/x²)
=4×((x+1/x)²-3)
=4×(16-3)
=4×13
=52;
很高兴为您解答,skyhunter002为您答疑解惑
如果本题有什么不明白可以追问,
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