越来越难了
(1)没处理好
>> syms x X b k positive;
>> p(x)=x*exp(-x^2/2/b^2)/b^2;P(x)=int(p(x),x,0,X);
>> Ex=int(x*p(x),x,0,inf);Dx=int((x-Ex)^2*p(x),x,0,inf);
>> vk=int(x^k*p(x),x,0,inf);miuk=int((x-Ex)^k*p(x),x,0,inf);
2023-12-10 21:46:09
>> syms x X b k positive;
>> p(x)=x*exp(-x^2/2/b^2)/b^2;P(x)=int(p(x),x,0,X);
>> Ex=int(x*p(x),x,0,inf);Dx=int((x-Ex)^2*p(x),x,0,inf);
>> vk=int(x^k*p(x),x,0,inf);miuk=int((x-Ex)^k*p(x),x,0,inf);