题目

已知函数f(x)=lg(x+1)(x>0),则f(x)的反函数为________. 答案：f-1(x)=10x-1(x>0) 解析:∵y=lg(x+1)(x>0), ∴y>0,且x+1=10y. ∴x=10y-1.∴反函数f-1(x)=10x-1(x>0).One’s style of the dress reveals the human obsession with both novelty and tradition. People use clothing to declare their membership in a particular social group; however, the rules for what is acceptable dress for that group may change. In affluent societies, this changing of the rules is the driving force behind fashions. By keeping up with fashions, that is, by changing their clothing style frequently but meanwhile, members of a group both satisfy their desire for novelty and obey the rules, thus demonstrating their membership in the group.There are some interesting variations (变种) regarding individual status. Some people, particularly in the West, consider themselves of such high status that they do not need to display it with their clothing. For example, many wealthy people in the entertainment industry appear in very casual clothes, such as the worn jeans and work boots of a manual laborer. However, it is likely that a subtle but important signal, such as an expensive wristwatch, will prevail over the message of the casual dress. Such an inverted (颠倒的)status display is most likely to occur where the person’s high status is conveyed in ways other than with clothing, such as having a famous face.【小题1】According to the author, fashions serve all the following purposes EXCEPTA．satisfying an interest in noveltyB．signaling a change in personal beliefsC．displaying membership in a social groupD．following traditional rules【小题2】Why does the author discuss individual status in paragraph 2?A．To state that individual’s status is not important in the WestB．To argue that individuals need not obey every fashion ruleC．To contrast the status of entertainers with that of manual laborersD．To explain how high status may involve an inverted status display【小题3】What’s the meaning of the underlined word?A．newnessB．conventionC．noblenessD．benzene