题目

函数f(x)＝是定义在(－1,1)上的奇函数，且f()＝. (1)确定函数f(x)的解析式； (2)用定义证明f(x)在(－1,1)上是增函数． 答案：解：(1)依题意得 即⇒ ∴f(x)＝. (2)证明：任取－1＜x1＜x2＜1， f(x1)－f(x2)＝－ ＝. ∵－1＜x1＜x2＜1， ∴x1－x2＜0,1＋x＞0,1＋x＞0， 又∵－1＜x1x2＜1，∴1－x1x2>0. ∴f(x1)－f(x2)＜0. ∴f(x)在(－1,1)上是增函数．26、The secret of his success is that he does everything ______.       A. curiously                   B. sensitively                 C. efficiently           D. imperfectly