优优班--学霸训练营 > 知识点挑题
全部资源
          排序:
          最新 浏览

          50条信息

            • 1.

              已知数列\(\left\{ {{a}_{n}} \right\}\)中,\({a}_{1}=2,{a}_{n+1}= \dfrac{4{a}_{n}-2}{3{a}_{n}-1}\left(n∈{N}^{*}\right) \),设\({{b}_{n}}=\dfrac{3{{a}_{n}}-2}{{{a}_{n}}-1}\).

              \((\)Ⅰ\()\)试写出数列\(\left\{ {{b}_{n}} \right\}\)的前三项;

              \((\)Ⅱ\()\)求证:数列\(\left\{ {{b}_{n}} \right\}\)是等比数列,并求数列\(\left\{ {{a}_{n}} \right\}\)的通项公式\({{a}_{n}}\);

              \((\)Ⅲ\()\)设\(\left\{ {{a}_{n}} \right\}\)的前\(n\)项和为\({{S}_{n}}\),求证:\(\dfrac{\left( n+1 \right)\cdot {{2}^{n+1}}-n-2}{{{2}^{n+1}}-1} < {{S}_{n}}\leqslant \dfrac{\left( n+2 \right)\cdot {{2}^{n-1}}-1}{{{2}^{n-1}}}\left( n\in N* \right)\).

            • 2.
              用反证法证明命题“若\(x^{2}-1=0\),则\(x=-1\)或\(x=1\)”时,假设命题的结论不成立的正确叙述是“ ______ ”\(.\)
            • 3.

              已知函数\(f\left(x\right)= \dfrac{1-x}{ax}+\ln x \)

              \((1)\)若函数\(f\left(x\right) \)在\([1,+∞) \)上为增函数,求正实数\(a\)的取值范围;

              \((2)\)当\(a=1\)时,求\(f\left(x\right) \)在\(\left[ \dfrac{1}{2},2\right] \)上的最大值和最小值;

              \((3)\)当\(a=1\)时,求证:当\(n\in N*,n > 1\)时都有 \(\ln \;n > \dfrac{1}{2}+ \dfrac{1}{3}+ \dfrac{1}{4}+⋯+ \dfrac{1}{n} \).

            • 4.

              已知\(α∈\left(0, \dfrac{π}{2}\right) \),\(β∈\left(0, \dfrac{π}{2}\right) \),且\(\dfrac{\alpha }{2(1+\cos \dfrac{\alpha }{2})} < \tan \beta < \dfrac{1-\cos \alpha }{\alpha }\),则

              A.\(\dfrac{\alpha }{4} < \beta < \dfrac{\alpha }{2}\)
              B.\(\dfrac{\alpha }{2} < \beta < \alpha \)

              C.\(\dfrac{\alpha }{8} < \beta < \dfrac{\alpha }{4}\)
              D.\(\dfrac{\alpha }{16} < \beta < \dfrac{\alpha }{8}\)
            • 5.

              设数列\(\{{{a}_{n}}\}\)的前\(n\)项和为\({{S}_{n}}\),数列\(\{{{b}_{n}}\}\)满足:\({{b}_{n}}=n{{a}_{n}}\),且数列\(\{{{b}_{n}}\}\)的前\(n\)项和为\((n-1){{S}_{n}}+2{{n}^{{}}}(n\in {{N}^{*}})\).

              \((1)\) 求\({{a}_{1}},{{a}_{2}}\)的值;

              \((2)\) 求证:数列\(\{{{S}_{n}}+2\}\)是等比数列;

              \((3)\) 抽去数列\(\{{{a}_{n}}\}\)中的第\(1\)项,第\(4\)项,第\(7\)项,\(……\),第\(3n-2\)项,\(……\)余下的项顺序不变,组成一个新数列\(\{{{c}_{n}}\}\),若\(\{{{c}_{n}}\}\)的前\(n\)项和为\({{T}_{n}}\),求证:\(\dfrac{12}{5} < \dfrac{{{T}_{n+1}}}{{{T}_{n}}}\leqslant \dfrac{11}{3}\).

            • 6.

              设函数\(f(x)= \dfrac{a{x}^{2}+bx+1}{x+c}(a > 0) \)为奇函数,且\(|f(x){|}_{min}=2 \sqrt{2} \),数列\(\{a\)\({\,\!}_{n}\)\(\}\)与\(\{b\)\({\,\!}_{n}\)\(\}\)满足如下关系:\({a}_{1}=2,{a}_{n+1}= \dfrac{f({a}_{n})-{a}_{n}}{2},{b}_{n}= \dfrac{{a}_{n}-1}{{a}_{n}+1} \).

              \((1)\)求\(f(x)\)的解析式;

              \((2)\)求数列\(\{{{b}_{n}}\}\)的通项公式\({{b}_{n}}\);

              \((3)\)记\({{S}_{n}}\)为数列\(\{{{a}_{n}}\}\)的前\(n\)项和,求证:对任意\(n\in {{N}^{*}}\)\({{S}_{n}} < n+\dfrac{3}{2}.\)

            • 7.

              已知函数\(f\left( x \right)=\dfrac{{lo}{{{g}}_{3}}\left( x+1 \right)}{x+1}\left( x > 0 \right)\)的图象上有一点列\({{P}_{n}}\left( {{x}_{n}},{{y}_{n}} \right)\left( n\in {{N}^{*}} \right)\),点\({{P}_{n}}\)在\(x\)轴上的射影是\({{Q}_{n}}\left( {{x}_{n}},0 \right)\),且\({{x}_{n}}=3{{x}_{n-1}}+2\) \((n\geqslant 2\)且\(n\in {{N}^{*}})\),\({{x}_{1}}=2\).

              \((1)\)求证:\(\left\{ {{x}_{n}}+1 \right\}\)是等比数列,并求出数列\(\left\{ {{x}_{n}} \right\}\)的通项公式;

              \((2)\)对任意的正整数\(n\),当\(m\in \left[ -1,1 \right]\)时,不等式\(3{{t}^{2}}-6mt+\dfrac{1}{3} > {{y}_{n}}\)恒成立,求实数\(t\)的取值范围.

              \((3)\)设四边形\({{P}_{n}}{{Q}_{n}}{{Q}_{n+1}}{{P}_{n+1}}\)的面积是\({{S}_{n}}\),求证:\(\dfrac{1}{{{S}_{1}}}+\dfrac{1}{2{{S}_{2}}}+\ldots +\dfrac{1}{n{{S}_{n}}} < 3\).

            • 8.

              下列结论不正确的是(    )

              \(①.\dfrac{1}{{{2}^{10}}}+\dfrac{1}{{{2}^{10}}+1}+\dfrac{1}{{{2}^{10}}+2}+\cdots +\dfrac{1}{{{2}^{11}}-1} > 1\)

              \(②.\)若\(|a| < 1\),则\(|a+b|-|a-b|\ > 2\)

              \(③.\lg 9\cdot \lg 11 < 1\)

              \(④.\)若\(x > 0,y > 0\),则\(\dfrac{x+y}{1+x+y} < \dfrac{x}{1+x}+\dfrac{y}{1+y}\)

              A.\(①②\)     
              B.\(①②③\)     
              C.\(①②④\)      
              D.\(①③\)
            • 9. 用反证法证明命题:“设实数\(a\),\(b\),\(c\)满足\(a+b+c=3\),则\(a\),\(b\),\(c\)中至少有一个数不小于\(1\)”时,第一步应写:假设 ______ .
            • 10.

              已知实数\(a,b,c\)满足\(a+b+c=2\),\({{a}^{2}}+{{b}^{2}}+{{c}^{2}}=4\),且\(a > b > c\)则\(a\)的取值范围是          

            0/40

            进入组卷