設(shè)函數(shù)f(x)=mx^2-mx-1,若對(duì)于m∈[1,3],f(x)<-m+5 恒成立,求x的取值范圍.
設(shè)函數(shù)f(x)=mx^2-mx-1,若對(duì)于m∈[1,3],f(x)<-m+5 恒成立,求x的取值范圍.
優(yōu)質(zhì)解答
mx^2-mx-1<-m+5
m(x^2-x+1)<6
∵x^2-x+1=(x-1/2)^2+3/4>0
∴m<6/(x^2-x+1)
∵m∈[1,3]
∴3<=m<6/(x^2-x+1)
∴(1-√5)/2