12.化下列二次积分为极坐标形式的二次积分:-|||-(1) (int )_(0)^1dx(int )_(0)^1f(x,y)dy;-|||-(2) (int )_(0)^2dx(int )_(x)^sqrt (3x)f(sqrt ({x)^2+(y)^2})dy;-|||-(3) (int )_(0)^1dx(int )_(1-x)^sqrt (1-{x^2)}f(x,y)dy;-|||-(4) (int )_(0)^1dx(int )_(0)^(x^2)f(x,y)dy.

12.化下列二次积分为极坐标形式的二次积分:-|||-(3) (int )_(0)^1dx(int )_(1-x)^sqrt (1-{x^2)}f(x,y)dy

在下列积分中改变累次积分的顺序:-|||-(1) (int )_(0)^2dx(int )_({x)^2x}f(x,y)dy;-|||-(2) (int )_(

求指导本题解题过程，谢谢您！28化二次积分 =(int )_(0)^1dx(int )_(0)^xf(sqrt ({x)^2+(y)^2})dy 为极坐标下的二

把下列积分化为极坐标形式, 并计算积分值: (3)(int )_(0)^1dx(int )_({x)^2}(({x)^2+(y)^2)}^-df

(int )_(0)^1dx(int )_(x)^1(e)^-(y^2)dy= () .-|||-

11.计算下列二重(二次)积分.-|||-(1) (int )_(0)^1dx(int )_(x)^3x(x-y)dy --|||-(2) iint x(e)^

二重积分(int )_(0)^1dx(int )_((x-1))^2f(x,y)dy,交换积分次序的结果是__________.二重积分交换积分次序的结果是__

24.证明: (int )_(0)^1dx(int )_(0)^xf(x-y)dy=(int )_(0)^1f(x)(1-x)dx-|||-"f(x-y)dy=

计算下列二重积分:-|||-(int )_(0)^1(x)^5dx(int )_({x)^2}^1(e)^-(y^2)dy

（请画图➕解答过程）3.交换积分次序:-|||-(1) (int )_(0)^1dx(int )_(x)^sqrt (x)f(x,y)dy;（请画图➕解答过程）