已知定義域為R的偶函數(shù)f(x)在區(qū)間[0,+∞)上是增函數(shù),若f(1)<f(lgx),則實數(shù)x的取值范圍是________.
分析:根據(jù)偶函數(shù)在對稱區(qū)間上單調(diào)性相反,結(jié)合已知我們可分析出函數(shù)的單調(diào)性,進(jìn)而根據(jù)f(1)<f(lgx),可得1<|lgx|,根據(jù)絕對值的定義及對數(shù)函數(shù)的單調(diào)性解不等式可得答案.
解答:∵函數(shù)f(x)是定義域為R的偶函數(shù)
且函數(shù)f(x)在區(qū)間[0,+∞)上是增函數(shù),
則函數(shù)f(x)在區(qū)間(-∞,0]上是減函數(shù),
若f(1)<f(lgx),
則1<|lgx|
即lgx<-1,或lgx>1
解得x∈
故答案為:
點評:本題考查的知識點是函數(shù)的奇偶性,函數(shù)的單調(diào)性,絕對值不等式的解法,對數(shù)函數(shù)的單調(diào)性,其中根據(jù)函數(shù)的性質(zhì)分析出1<|lgx|是解答本題的關(guān)鍵.