x²-2x-3>0(x+1)(x-3)>0x3真数在(-∞,-1)上递减,在(3,+∞)上递增底数1/2是递减的根据复合函数单调性：同增异减可知f(x)的单调递增区间为(-∞,-1),单调递减区间为(3,+∞)由上可知f(x)在【5,8】上是递减的所以,最...