y=x^2+2mx+1/3x^2-2x+3的任意实数x都有|y|<5求m的取值范围

来源:百度知道 编辑:UC知道 时间:2024/06/21 08:33:11
y=(x^2+2mx+1)/(3x^2-2x+3)的任意实数x都有|y|<5,求m的取值范围

3x^2-2x+3=3(x-1/3)^2+3-1/3>0

y=x^2+2mx+1/3x^2-2x+3<5
x^2+2mx+1<5(3x^2-2x+3)
14x^2-(10+2m)x+14>0
△=(10+2m)^2-4*14*14<0
-28<10+2m<28
-19<m<9

y=x^2+2mx+1/3x^2-2x+3>-5
x^2+2mx+1>-5(3x^2-2x+3)
16x^2+(2m-10)x+16>0
△=(2m-10)^2-4*16*16<0
-32<(2m-10)<32
-11<m<21

所以,m的取值范围:-11<m<9