题目设随机变量X与Y相互独立,X~N(1,2),Y~N(1,1),则随机变量Z=2X-Y的分布为A. N(1,8)B. N(1,9)C. N(1,3)D. N(3,5)设随机变量X与Y相互独立,X~N(1,2),Y~N(1,1),则随机变量Z=2X-Y的分布为A. N(1,8)B. N(1,9)C. N(1,3)D. N(3,5)题目解答答案B. N(1,9)