已知y=f(x)y = f(x)y=f(x)是定义在区间[−3,6][−3,6][−3,6]上的单调函数,值域为[3,9][3,9][3,9],则其反函数x=φ(y)x = \varphi(y)x=φ(y)的定义域为(). (A)[−3,6][−3,6][−3,6] (B)[3,9][3,9][3,9] (C)(−3,6)(−3,6)(−3,6) (D)[3,9)[3,9)[3,9)
设f(x)=ex−1xf(x)=\dfrac{e^x - 1}{x}f(x)=xex−1,则x=0x = 0x=0是f(x)f(x)f(x)的(). (A)连续点 (B)可去间断点 (C)跳跃间断点 (D)无穷间断点
极限limx→∞x−12x+1=\lim\limits_{x \to \infty} \dfrac{x - 1}{2x + 1}=x→∞lim2x+1x−1=(). (A)1 (B)−1−1−1 (C)12\dfrac{1}{2}21 (D)