y=[4/(x^2)] +{9/[400-(x^2)]}

学习时间:2026-10-01 13:54:45 阅读：4630

y=[4/(x^2)] +{9/[400-(x^2)]}讨论其单调性,并求出X值使y最小

慈祥的小笼包

2026-10-01 13:54:45

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柯西不等式呀~（4/x²+9/(400-x²)）×(x²+(400-x))≥(2+3)²=25y≥25/400=1/16取等条件是（4/x²）/(9/(400-x²)) = (x²)/(400-x²)x=4倍根号10