CRB是x<=a,x>=a+2即缺了集合B中的衫知这个区间aAU(CRB)=R所以A要包含这一段所以1<乱塌洞=a且a+2<=5所以哗枯1<=a<=3
分母裂档不等于0x²-3x+2≠0(x-1)(x-2)≠0x≠1,x≠2所伍姿以定义域(-∞,1)∪(1,2)∪(2,+∞)根号下大于等于,分母不等于0(4-x)/(x-1)≥0即(x-4)/(x-1)≤0(x-4)(x-1)≤01≤x≤4x-1≠0所以1定腔源绝义域(1,4]