∵y=log1/2(u)为减函数∴y=log1/2(x^2-ax-a)在区间(-∞,-1/2)上递增即u=x^2-ax-a在区间(-∞,-1/2)上递减u=x^2-ax-a的对称轴x=a/2,对应图象(抛物线)开口向上,在(-∞,a/2)递减∴a/2>=-1/2,即a>=-1又在(-无穷,-1/2]上u>...