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已知x^2n=2,求(3x^3n)²-4(x²)^2n的值
人气:462 ℃ 时间:2020-02-03 08:34:14
解答
∵x^(2n)=2
∴(3x^3n)²-4(x²)^2n
=3²x^(2×3n)-4*[x^(2n)]^2
=9*[x^(2n)]^3-4*[x^(2n)]^2
=9*2^3-4*2^2
=72-16
=56
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