Question

函數(shù)的值域?yàn)?u>           ．

Answer 1

[―2, ―1]

試題分析：因?yàn)?img src="http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240117334831058.png" style="vertical-align:middle;" />，而對(duì)數(shù)的底數(shù)，故，函數(shù)的值域?yàn)閇―2, ―1]。
點(diǎn)評(píng)：小綜合題，本題綜合考查指數(shù)函數(shù)、對(duì)數(shù)函數(shù)的性質(zhì)及函數(shù)的值域，涉及指數(shù)函數(shù)、對(duì)數(shù)函數(shù)問(wèn)題，首先要關(guān)注底數(shù)的取值情況。