1.4^a=8;log2(4^a)=log2(8);2a = log2(2�0�6) = 3;a = 3/2;1.5^a = (3/2)^(3/2)=(3/2)√(3/2);0.8 = 2/5;(2/5)/(1.5^a) = 8/15√6<1;所以1.5^a>0.82.x-2>0;即x>2;1≤log2(x-2)≤log2(14);log2(2)≤log2(x-2)≤log2(14);2≤x-2≤14;4≤x≤16;即定义域为[4,16