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log1/3(x²-5x+7)>0=log1/3(1)
易知y=log1/3(x)在(0,+∞)上单调递减
令f(x)=x²-5x+7,△=25-280
故f(x)恒大于0
故x²-5x+7
//-----------------------------------------分割线----------------------------------------------------------------
log1/3(x²-5x+7)>0=log1/3(1)
易知y=log1/3(x)在(0,+∞)上单调递减
令f(x)=x²-5x+7,△=25-280
故f(x)恒大于0
故x²-5x+7