K心 ec7计算∫∫ e ddda Qr +y 2由z=√x2+y2,z=1,z=2围成 Method1 =91+_2={(x,y,z)1sz≤2,x2+y≤1 +{(x,y,z)|x2+y2≤z≤2,1≤x2+y2≤4 ={(r,B,z)|1≤z≤2,0≤r≤1,0≤6≤2} +{(7,6,)rsz≤2,1sr≤2,0≤6s2my 原式=∫rot=2m2 Q ,y o desdrhe'dz+ o def drle'dz7. , 2 2   + dxdydz x y e ex z 计算 , 1, 2 . 由z = x 2 + y 2 z = z = 围成 Method1. x y z o  = 1 + 2 {( , , ) | 1 2, 1} 2 2 = x y z  z  x + y  {( , , ) | 2,1 4} 2 2 2 2 + x y z x + y  z   x + y  = {(r, ,z) |1  z  2,0  r  1,0    2 } +{(r, ,z) |r  z  2,1  r  2,0    2 }    = rdrd dz r e z 原式  =    2 1 1 0 2 0 d dr e dz  z  +    2 2 1 2 0 r z d dr e dz   2 . 2 = e