若單調(diào)函數(shù)y=f(x+1)的圖象經(jīng)過點(-2,1),則函數(shù)y=f-1(x-1)的圖象必過點( )
A.(2,-1)
B.(-1,2)
C.(2,-2)
D.(1,-2)
【答案】分析:由題意,函數(shù)y=f(x+1)的圖象可看作函數(shù)f(x)的圖象左移一個單位而得到,由此求出函數(shù)f(x)的圖象過的定點坐標(biāo),再由反函數(shù)得出函數(shù)y=f-1(x)的圖象所過的定點,利用平移的知識得出函數(shù)y=f-1(x-1)的圖象所過的定點的坐標(biāo),選出正確選項
解答:解:單調(diào)函數(shù)y=f(x+1)的圖象經(jīng)過點(-2,1),可得單調(diào)函數(shù)y=f(x)的圖象經(jīng)過點(-1,1),
由反函數(shù)的性質(zhì)知函數(shù)y=f-1(x)的圖象所過的定點坐標(biāo)是(1,-1)
又函數(shù)y=f-1(x-1)的圖象由函數(shù)y=f-1(x)的圖象右移一個單位而得到,
故函數(shù)y=f-1(x-1)的圖象必過點(2,-1)
觀察四個選項知,A選項是正確的
故選A
點評:本題考查反函數(shù)及函數(shù)圖象的變換,正確解答本題,關(guān)鍵是熟練掌握反函數(shù)的定義,及函數(shù)圖象變換的規(guī)則,本題用到了轉(zhuǎn)化的思想,通過兩個函數(shù)的f(x)的圖象特征與函數(shù)y=f-1(x)的圖象特征得出了函數(shù)y=f-1(x-1)的圖象必過的定點,對問題進行研究時可借鑒本題的化整為零來解決的方式.