若函數(shù)f(x)的圖象與對(duì)數(shù)函數(shù)y=log4x的圖象關(guān)于直線x+y=0對(duì)稱,則f(x)的解析式為f(x)=________.
y=-4
-x分析:先設(shè)f(x)上一點(diǎn)(x,y),求這個(gè)點(diǎn)關(guān)于x+y=0的對(duì)稱點(diǎn),則根據(jù)題意該對(duì)稱點(diǎn)在函數(shù)y=log
4x的圖象上,滿足函數(shù)y=log
4x的解析式,從而可求出點(diǎn)(x,y)的軌跡方程
解答:設(shè)函數(shù)f(x)的圖象上一點(diǎn)(x,y),則點(diǎn)(x,y)關(guān)于x+y=0的對(duì)稱點(diǎn)(x',y')在對(duì)數(shù)函數(shù)y=log
4x的圖象
由題意知
,解得x'=-y,y'=-x
又∵點(diǎn)(x',y')在對(duì)數(shù)函數(shù)y=log
4x的圖象
∴-x=log
4(-y)
∴-y=4
-x
∴y=-4
-x
故答案為:y=-4
-x
點(diǎn)評(píng):本題考查函數(shù)的圖象與性質(zhì),求函數(shù)的解析式.解題的關(guān)鍵是會(huì)求點(diǎn)個(gè)關(guān)于直線的對(duì)稱點(diǎn).屬簡單題