题目设随机变量 -[ dfrac (-1)(a)bdfrac (1)(6)] 且 ||X|=1 =P X=0 , 则常数a,b的值为-|||-bigcirc A. =dfrac (1)(2) =dfrac (1)(2)-|||-bigcirc B. =dfrac (1)(4) ,=dfrac (1)(3)-|||-bigcirc C. =dfrac (1)(3) ,=dfrac (1)(2)-|||-bigcirc D. =dfrac (1)(2) =dfrac (1)(4)题目解答答案