共50条信息
设\(a_{1}\),\(a_{2}\),\(…\),\(a_{n}\)是\(1\),\(2\),\(…\),\(n(n\geqslant 2,n∈N^{*})\)的一个排列,求证:\( \dfrac{1}{2}+ \dfrac{2}{3}+…+ \dfrac{n-1}{n}\leqslant \dfrac{a_{1}}{a_{2}}+ \dfrac{a_{2}}{a_{3}}+…+ \dfrac{a_{n-1}}{a_{n}}\).
已知\(a > 0\),\(b > 0\),\(c > 0\),函数\(f(x)=|x+a|-|x-b|+c\)的最大值为\(10\).
\((1)\)求\(a+b+c\)的值\(;\)
\((2)\)求\(\dfrac{1}{4}(a-1)^{2}+(b-2)^{2}+(c-3)^{2}\)的最小值,并求出此时\(a\),\(b\),\(c\)的值.
设\(a\),\(b\),\(c\)为正数,且\(a+2b+3c=13\),则\(\sqrt{3a}+\sqrt{2b}+\sqrt{c}\)的最大值为\((\) \()\)
解答题
\((1)\)已知\(x+y+z=1\),求证:\({{x}^{2}}+{{y}^{2}}+{{z}^{2}}\geqslant \dfrac{1}{3}\).
\((2)\)已知\(a > 0\),\(\dfrac{1}{b}-\dfrac{1}{a} > 1\),求证:\(\sqrt{1+a} > \dfrac{1}{\sqrt{1-b}}\).
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