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            • 1.

              已知曲线\(f(x)= \dfrac{{\log }_{2}(x+1)}{x+1}(x > 0) \)上有一点列\({P}_{n}({x}_{n},{y}_{n})(n∈{N}_{∗}) \),过点\({P}_{n} \)在\(x \)轴上的射影是\({Q}_{n}({x}_{n},0) \),且\({x}_{1}+{x}_{2}+{x}_{3}+⋯{x}_{n}={2}^{n+1}−n−2. (n∈{N}_{∗}) \)

              \((1)\)求数列\(\{{x}_{n}\} \)的通项公式

              \((2)\)设四边形\({P}_{n}{Q}_{n}{Q}_{n+1}{P}_{n+1} \)的面积是\({S}_{n} \),求\({S}_{n} \)

              \((3)\)在\((2) \)条件下,求证:\(\dfrac{1}{{S}_{1}}+ \dfrac{1}{2{S}_{2}}+⋯+ \dfrac{1}{n{S}_{n}} < 4. \)

            • 2.

              已知数列\(\{a_{n}\}\)满足\(a_{1}=1\),\(a_{n+1}=3a_{n}+1\).

              \((1)\)证明\(\left\{ {{a}_{n}}+\dfrac{1}{2} \right\}\)是等比数列,并求\(\{a_{n}\}\)的通项公式;

              \((2)\)证明:\(\dfrac{1}{{{a}_{1}}}+\dfrac{1}{{{a}_{2}}}+\cdots +\dfrac{1}{{{a}_{n}}} < \dfrac{3}{2}\).

            • 3.

              曲线\(y=\sqrt{x}\)上点\({{P}_{1}},{{P}_{2}},\cdots {{P}_{n}}\)与\(x\)轴上点\({{Q}_{1}},{{Q}_{2}},\cdots {{Q}_{n}}\)构成一列正三角形,即\(\Delta O{{P}_{1}}{{Q}_{1}},\Delta {{Q}_{1}}{{P}_{2}}{{Q}_{2}},\cdots \Delta {{Q}_{n-1}}{{P}_{n}}{{Q}_{n}}\),设\(\Delta O{{P}_{1}}{{Q}_{1}}\)的边长为\({{a}_{1}}\),正三角形\(\Delta {{Q}_{n-1}}{{P}_{n}}{{Q}_{n}}\)的边长为\({{a}_{n}}\)


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

              \((2)\)求数列\(\left\{ {{a}_{n}} \right\}\)的通项公式

              \((3)\)证明:\(\dfrac{1}{{{a}_{1}}^{2}}+\dfrac{1}{{{a}_{2}}^{2}}+\cdots +\dfrac{1}{{{a}_{n}}^{2}} < \dfrac{63}{16}\)

            • 4. 用反证法证明:若实数\(a\),\(b\),\(c\),\(d\)满足\(a+b=c+d=1\),\(ac+bd > 1\),那么\(a\),\(b\),\(c\),\(d\)中至少有一个小于\(0\),下列假设正确的是\((\)  \()\)
              A.假设\(a\),\(b\),\(c\),\(d\)都大于\(0\)
              B.假设\(a\),\(b\),\(c\),\(d\)都是非负数
              C.假设\(a\),\(b\),\(c\),\(d\)中至多有一个小于\(0\)
              D.假设\(a\),\(b\),\(c\),\(d\)中至多有两个大于\(0\)
            • 5.

              已知数列\(\left\{ {{a}_{n}} \right\}\)满足\({{a}_{1}}=2\),且\({{a}_{n}}=2{{a}_{n-1}}+{{2}^{n}}\)\((\)\(n\geqslant 2\),且\(n\in {{N}^{*}}\)\().\)

              \((\)Ⅰ\()\)求证:数列\(\left\{ \dfrac{{{a}_{n}}}{{{2}^{n}}} \right\}\)是等差数列,并求数列\(\left\{ {{a}_{n}} \right\}\)的通项公式\({{a}_{n}}\);

              \((\)Ⅱ\()\)记\({{b}_{n}}={{(\dfrac{{{2}^{n}}}{{{a}_{n}}})}^{2}}\),设数列\(\left\{ {{b}_{n}} \right\}\)的前\(n\)项和为\({{S}_{n}}\),求证:\({{S}_{n}} < 2\).
            • 6.

              已知曲线\(f(x)=\dfrac{{\log }_{2}\left(x+1\right)}{x+1} (x > 0)\)上有一点列\(P_{n}(x_{n},y_{n})(n∈N*)\),过点\(P_{n}\)在\(x\)轴上的射影是\(Q_{n}(x_{n},0)\),且\(x_{1}+x_{2}+x_{3}+…+x_{n}=2^{n+1}-n-2.(n∈N*)\)

              \((1)\)求数列\(\{x_{n}\}\)的通项公式;

              \((2)\)设四边形\(P_{n}Q_{n}Q_{n+1}P_{n+1}\)的面积是\(S_{n}\),求\(S_{n}\);

              \((3)\)在\((2)\)条件下,求证:\(\dfrac{1}{{S}_{1}} \) \(+\dfrac{1}{2{S}_{2}} +…+\dfrac{1}{n{S}_{n}} < 4\).

            • 7.

              已知数列\(\{a_{n}\}\)为公差不为零的等差数列,\(a_{2}=3\)且\(a_{1}\),\(a_{3}\),\(a_{7}\)成等比数列.

              \((\)Ⅰ\()\)求数列\(\{a_{n}\}\)的通项公式;

              \((\)Ⅱ\()\)若数列\(\{b_{n}\}\)满足\({{b}_{n}}=\dfrac{10}{10{{a}_{n}}{{a}_{n+}}_{1}+1}\),记数列\(\{b_{n}\}\)的前\(n\)项和为\(S_{n}\),求证:\({{S}_{n}} < \dfrac{1}{2}\).

            • 8.

              用反证法证明命题:“设\(a,b\in R\),若\({{a}^{2}}+{{b}^{2}}=0\),则\(a,b\)全为\(0\)”时,其反设正确的是

              A.\(a,b\)至少有一个不为零                   
              B.\(a,b\)至少有一个为零      

              C.\(a,b\)全不为零                           
              D.\(a,b\)中只有一个为零
            • 9.

              设数列\(\left\{ {{a}_{n}} \right\}\)满足\({{a}_{1}}=\dfrac{3}{2}\),\({{a}_{n+1}}=\ln \dfrac{{{a}_{n}}+1}{3}+2(n\in {{N}^{*}})\).

              \((\)Ⅰ\()\)证明:\({{a}_{n+1}}\geqslant \dfrac{3{{a}_{n}}}{{{a}_{n}}+1}\);

              \((\)Ⅱ\()\)记数列\(\{\dfrac{1}{{{a}_{n}}}\}\)的前\(n\)项和为\({{S}_{n}}\),证明:\({{S}_{n}} < \dfrac{n}{2}+\dfrac{1}{4}\).

            • 10.

              已知点\({{P}_{n}}({{a}_{n}},{{b}_{n}})(n\in {{N}^{+}})\)在直线\(l:y=3x+1\)上,\({{P}_{1}}\)是直线\(l\)与\(y\)轴的交点,数列\(\left\{ {{a}_{n}} \right\}\)是公差为\(1\)的等差数列.

              \((\)Ⅰ\()\)求数列\(\left\{ {{a}_{n}} \right\}\),\(\left\{ {{b}_{n}} \right\}\)的通项公式;

              \((\)Ⅱ\()\)求证:\(\dfrac{1}{{{\left| {{P}_{1}}{{P}_{2}} \right|}^{2}}}+\dfrac{1}{{{\left| {{P}_{1}}{{P}_{3}} \right|}^{2}}}+......+\dfrac{1}{{{\left| {{P}_{1}}{{P}_{n+1}} \right|}^{2}}} < \dfrac{1}{5}\)

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