A: $\frac{n}{\ln n}$
B: ${{(-1)}^{n}}{{n}^{2}}+n$
C: $n\sin \frac{n\text{ }\!\!\pi\!\!\text{ }}{2}$
D: $\frac{{{\text{e}}^{n}}}{n!}$
举一反三
- 下列数列中，不是无穷大的是 A: $\frac{n}{\ln n}$ B: $-{{n}^{2}}+n$ C: $\frac{n({{n}^{\frac{7}{3}}}+1)}{{{n}^{\frac{15}{4}}}}$ D: ${{(-1)}^{n}}{{n}^{3}}+{{n}^{2}}-10n$
- 1．下列数列中，收敛但极限不为$1$的是 A: ${{(2+\frac{1}{n})}^{\frac{1}{n}}}$ B: ${{n}^{\frac{1}{n}}}$ C: $\frac{1}{{{n}^{2}}+1}+\frac{2}{{{n}^{2}}+2}+\cdots +\frac{n}{{{n}^{2}}+n}$ D: $\frac{{{(n!)}^{2}}}{{{n}^{n}}}$
- 函数\(f(x) = x^2,\; x \in [-\pi,\pi]\)的Fourier级数为 A: \(\frac{\pi^2}{3}+4\Sigma_{n=1}^{\infty} \frac{(-1)^n}{n^2} \sin nx ,\; x \in [-\pi,\pi]\) B: \(\frac{\pi^2}{3}+4\Sigma_{n=1}^{\infty} \frac{(-1)^n}{n^2} \cos nx ,\; x \in [-\pi,\pi]\) C: \(\frac{2\pi^2}{3}+4\Sigma_{n=1}^{\infty} \frac{(-1)^n}{n^2} \sin nx ,\; x \in [-\pi,\pi]\) D: \(\frac{2\pi^2}{3}+4\Sigma_{n=1}^{\infty} \frac{(-1)^n}{n^2} \cos nx ,\; x \in [-\pi,\pi]\)
- 5. 下列数列中，极限为$1$的是 A: $\frac{n}{{{a}^{n}}}\ \ (a\gt 1)$ B: ${{a}^{\frac{1}{n}}}\ \ (a\gt 1)$ C: $\frac{\sin {{n}^{2}}}{n}$ D: $\frac{n\sqrt{n+1}}{\sqrt{n}(2n-1)}$
- 设`\n`阶方阵`\A`满足`\|A| = 2`，则`\|A^TA| = ,|A^{ - 1}| = ,| A^ ** | = ,| (A^ ** )^ ** | = ,|(A^ ** )^{ - 1} + A| = ,| A^{ - 1}(A^ ** + A^{ - 1})A| = `分别等于（ ） A: \[4,\frac{1}{2},{2^{n - 1}},{2^{{{(n - 1)}^2}}},2{(\frac{3}{2})^n},\frac{{{3^n}}}{2}\] B: \[2,\frac{1}{2},{2^{n - 1}},{2^{{{(n + 1)}^2}}},2{(\frac{3}{2})^n},\frac{{{3^n}}}{2}\] C: \[4,\frac{1}{2},{2^{n + 1}},{2^{{{(n - 1)}^2}}},2{(\frac{3}{2})^{n - 1}},\frac{{{3^n}}}{2}\] D: \[2,\frac{1}{2},{2^{n - 1}},{2^{{{(n - 1)}^2}}},2{(\frac{3}{2})^{n - 1}},\frac{{{3^n}}}{2}\]
内容
- 0
函数$f(x)=\arcsin(\sin x)$的傅里叶级数展开式为 A: $x$ B: $$\frac{4}{\pi}\sum_{n=0}^{\infty}\frac{(-1)^n\sin(2n+1)x}{(2n+1)^2}$$ C: $$\frac{4}{\pi}\sum_{n=1}^{\infty}\frac{(-1)^n\sin(2n+1)x}{(2n+1)^2}$$ D: $$\frac{4}{\pi}\sum_{n=1}^{\infty}\frac{(-1)^{n-1}\sin(2n+1)x}{(2n+1)^2}$$
- 1
函数$y=\ln x$的$n$阶导数为 A: $\frac{(n-1)!}{x^n}$ B: $\frac{n!}{x^n}$ C: $(-1)^{n-1}\frac{(n-1)!}{x^n}$ D: $(-1)^n\frac{(n-1)!}{x^n}$
- 2
Solve $n \in \mathbb{N}, \int_0^{\frac{\pi}{2}}(\sin^n{x}-\cos^n{x})dx=$ :<br/>______
- 3
${X_1},{X_2},...,{X_n}$是来自均匀分布X~U(-a,a)的样本，用矩估计法估计参数a为() A: ${(\frac{3}{n}\sum\limits_{k = 1}^n {x_k^2} )^{\frac{1}{2}}}$ B: ${(\frac{2}{n}\sum\limits_{k = 1}^n {x_k^2} )^{\frac{1}{2}}}$ C: ${(\frac{3}{n}\sum\limits_{k = 1}^n {x_k} )^{\frac{1}{2}}}$ D: ${(\frac{2}{n}\sum\limits_{k = 1}^n {x_k} )^{\frac{1}{2}}}$
- 4
下面级数求和错误的是 A: $\sum_{n=0}^\infty q^n = \frac{1}{1-q} (0\lt q\lt1) $ B: $\sum_{n=1}^\infty \frac{x^{2^{n-1}}}{1-x^{2^n}} = \frac{x}{1-x} (|x|\lt 1) $ C: $\sum_{n=1}^\infty \frac{1}{{n!}} = e $ D: $\sum_{n=1}^\infty \frac{x^{2^{n-1}}}{1-x^{2^n}} = \frac{1}{1-x} (x>1) $