A. $\int_{\theta_1}^{\theta_2} f(r \cos \theta, r \sin \theta)\, d\theta $
B. $\int_{\theta_1}^{\theta_2} f(x, y)\sqrt{1 + y^2} \, dx $
C. $\int_{\theta_1}^{\theta_2} f(r \cos \theta, r \sin \theta)\, r \, d\theta $
D. $\int_{\theta_1}^{\theta_2} f(r \cos \theta, r \sin \theta)\sqrt{r^2 + r'^2} \, d\theta $
判断设 hat(theta_1), hat(theta_2)是 theta的无偏估计量,若 D(theta_1) > D(theta_2)，则 hat(thet
设总体 X 的概率密度为 f(x)= } (3x^2)/(theta^3), & 0 leq x leq theta, 0, & (其他)A. $\overl
设 theta_1, theta_2为未知参数 theta的两个估计量，若对任意的样本容量 n，有 n, D(theta_1)A. 对B. 错
设总体 X 的概率密度为 f(x; theta)= } (5-2theta)x, & 0 leq xA. 2.5B. 2.1C. 1.7D. 1.9
设总体X的概率密度f(x;theta)=}(3)/(theta^3)x^2, & 0leq xleqtheta, 0, & (其他.)A. $2\overli
设 D: 0 leq r leq 1, 0 leq theta leq (pi)/(2)，根据二重积分的几何意义，iint_(D) sqrt(1-r^2) r
theta_1是参数 theta的无偏估计量，且 D(theta_1) > 0，则A. $$ $\theta\_1^2$是 $\theta^2$的无偏估计量
(int )_(dfrac {pi )(4)}^dfrac (pi {2)}dtheta (int )_(0)^cot theta (r)^2cos theta
12.设曲线的极坐标方程为 rho =dfrac (1)(pi )(1-cos theta ), 求曲线在 theta =dfrac (pi )(2) 处的切线
_(1)^theta +(K)_(2)^theta C. _(1)^theta /({K)_(2)}^theta D. _(2)/(K)_(1)^theta