题目内容

5.$\int_{\,0}^{\,\,1}{\frac{\text{d}x}{{{\text{e}}^{x}}+{{\text{e}}^{-x}}}=}$().

A. $\arctan \text{e}+\frac{\text{ }\!\!\pi\!\!\text{ }}{2}$
B. $\arctan \text{e}-\frac{\text{ }\!\!\pi\!\!\text{ }}{2}$
C. $\arctan \text{e}+\frac{\text{ }\!\!\pi\!\!\text{ }}{4}$
D. $\arctan \text{e}-\frac{\text{ }\!\!\pi\!\!\text{ }}{4}$

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6.$\int_{0}^{1}{\frac{\arcsin \sqrt{x}}{\sqrt{x(1-x)}}\,\,\text{d}x}$().

A. ${{\left( \frac{\text{ }\!\!\pi\!\!\text{ }}{2} \right)}^{2}}$
B. $\frac{\text{ }\!\!\pi\!\!\text{ }}{2}$
C. ${{\left( \frac{\text{ }\!\!\pi\!\!\text{ }}{4} \right)}^{2}}$
D. $\frac{\text{ }\!\!\pi\!\!\text{ }}{4}$

4.设$S(x)=\sum\limits_{n=1}^{\infty }{{{(-1)}^{n-1}}n(n+1){{x}^{n}}}$,$x\in (-1,\ 1)$,则$S(\frac{1}{2})=$().

A. $\frac{18}{64}$
B. $\frac{27}{64}$
C. $\frac{4}{27}$
D. $\frac{8}{27}$

5.设函数$f(x)={{x}^{2}}$,$x\in [0,\ 1]$,而$S(x)=\frac{{{a}_{0}}}{2}+\sum\limits_{n=1}^{\infty }{{{a}_{n}}\cos n\text{ }\!\!\pi\!\!\text{ }x}$,$x\in (-\infty ,+\infty )$,其中${{a}_{n}}=2\int_{0}^{1}{f(x)\cos n\text{ }\!\!\pi\!\!\text{ }x\text{d}x}\ \ (n=0,\ 1,\ 2,\cdots )$,则$S(-1)=$().

A. $-1$
B. $-\frac{1}{2}$
C. $\frac{1}{2}$
D. $1$

2.$\underset{n\to +\infty }{\mathop{\lim }}\,n[{{(1+\frac{1}{n})}^{\frac{n}{2}}}-\sqrt{\text{e}}]$=().

A. $0$
B. $-\frac{\sqrt{\text{e}}}{4}$
C. $\frac{\sqrt{\text{e}}}{4}$
D. $\frac{\sqrt{\text{e}}}{2}$

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