(1)y=1/log2 (x)
x在真数上,故x>0
log2 (x)在分母上,故log2(x)≠0即x≠1
所以定义域为(0,1)∪(1,+∞)
(2)y=log2 [1/(1-3x)]
真数1/(1-3x)>0即1-3x>0解得x