问题
填空题
函数y=lg（2-2x）的单调递减区间是______．
答案
由2-2x＞0得x＜1，
所以函数y=lg（2-2x）的定义域为（-∞，1），
y=lg（2-2x）由y=lgu，u=2-2x复合而成，
且y=lgu递增，u=2-2x在（-∞，1）上递减，
所以y=lg（2-2x）的单调递减区间是（-∞，1）．
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函数y=lg（2-2x）的单调递减区间是______．
由2-2x＞0得x＜1，
所以函数y=lg（2-2x）的定义域为（-∞，1），
y=lg（2-2x）由y=lgu，u=2-2x复合而成，
且y=lgu递增，u=2-2x在（-∞，1）上递减，
所以y=lg（2-2x）的单调递减区间是（-∞，1）．
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