2016年数学2考研真题解析如下:
一、选择题
1. 下列函数中,连续且可导的是( )
A. \(f(x) = |x|\) B. \(f(x) = \sqrt{x}\) C. \(f(x) = \frac{1}{x}\) D. \(f(x) = x^2\)
答案:A
2. 下列级数中,收敛的是( )
A. \(\sum_{n=1}^{\infty} \frac{1}{n^2}\) B. \(\sum_{n=1}^{\infty} \frac{1}{n}\) C. \(\sum_{n=1}^{\infty} \frac{1}{n^3}\) D. \(\sum_{n=1}^{\infty} \frac{1}{n^4}\)
答案:A
3. 设\(f(x) = \ln(x+1)\),则\(f'(1) = \)
A. 1 B. 0 C. -1 D. \(\frac{1}{2}\)
答案:B
二、填空题
1. 设\(f(x) = x^3 - 3x^2 + 2x\),则\(f'(x) = \)
答案:\(3x^2 - 6x + 2\)
2. 设\(f(x) = e^x\),则\(f''(x) = \)
答案:\(e^x\)
三、解答题
1. 求函数\(f(x) = x^3 - 3x^2 + 2x\)的极值。
答案:\(f'(x) = 3x^2 - 6x + 2\),令\(f'(x) = 0\),得\(x = 1\)或\(x = \frac{2}{3}\)。当\(x < \frac{2}{3}\)时,\(f'(x) > 0\),\(f(x)\)单调递增;当\(\frac{2}{3} < x < 1\)时,\(f'(x) < 0\),\(f(x)\)单调递减;当\(x > 1\)时,\(f'(x) > 0\),\(f(x)\)单调递增。因此,\(f(x)\)在\(x = \frac{2}{3}\)处取得极大值\(f(\frac{2}{3}) = -\frac{8}{27}\),在\(x = 1\)处取得极小值\(f(1) = 0\)。
2. 求下列极限:
(1)\(\lim_{x \to 0} \frac{\sin x}{x}\)
答案:1
(2)\(\lim_{x \to \infty} \frac{e^x}{x^2}\)
答案:\(\infty\)
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