题目
二次积分 int_(0)^1 dx int_(x^2)^x (x^2 + y^2)^-(1)/(2) , dy 可以写成A. int_(0)^(pi)/(4) mathrm(d)theta int_(0)^sec theta tan theta r^3 , mathrm(d)rB. int_(0)^(pi)/(4) mathrm(d)theta int_(0)^sec theta tan theta r^2 , mathrm(d)rC. int_(0)^(pi)/(4) mathrm(d)theta int_(0)^sec theta tan theta r , mathrm(d)rD. int_(0)^(pi)/(4) mathrm(d)theta int_(0)^sec theta tan theta mathrm(d)r
二次积分 $\int_{0}^{1} dx \int_{x^2}^{x} (x^2 + y^2)^{-\frac{1}{2}} \, dy$ 可以写成
A. $\int_{0}^{\frac{\pi}{4}} \mathrm{d}\theta \int_{0}^{\sec \theta \tan \theta} r^3 \, \mathrm{d}r$
B. $\int_{0}^{\frac{\pi}{4}} \mathrm{d}\theta \int_{0}^{\sec \theta \tan \theta} r^2 \, \mathrm{d}r$
C. $\int_{0}^{\frac{\pi}{4}} \mathrm{d}\theta \int_{0}^{\sec \theta \tan \theta} r \, \mathrm{d}r$
D. $\int_{0}^{\frac{\pi}{4}} \mathrm{d}\theta \int_{0}^{\sec \theta \tan \theta} \mathrm{d}r$
题目解答
答案
D. $\int_{0}^{\frac{\pi}{4}} \mathrm{d}\theta \int_{0}^{\sec \theta \tan \theta} \mathrm{d}r$