6.二重积分计算的两种积分顺序r=∫/(x,p)dy D:x1()≤x≤x2() D:y1(x)≤y≤y2(x) ≤y≤d a≤x<b y2(x) x10y) x2() D D y1(x) x b x2(y) J2 f(x, y)dx f(x, y)dy x1(y) 囧0 y x c d y d c dy D D: y1 (x) y y2 (x) a x b 0 y x I = a b y1 (x) y2(x) D x1 (y) x2(y) x ( ) ( ) ( , )d y x y x I = f x y y 6. 二重积分计算的两种积分顺序 . = D I f (x, y)dxdy ( ) ( ) ( )d x y x y f x, y x D: x1 (y) x x2 (y) c y d