Đáp án:
`g)H(x)=|1/2x-3|-1/2`
Vì `|1/2x-3|>=0`
`=>H(x)>=-1/2`
Dấu "=' xảy ra khi `1/2x=3<=>x=6`
`h)K(x)=|3x-2|+|4-6x|`
`=|3x-2|+2|2-3x|`
`=3|3x-2|>=0`
Dấu "=" xảy ra khi `3x=2<=>x=2/3`
`j)M(x)=|x-1|+(x^2-1)^2`
Vì `|x-1|>=0`
`(x^2-1)^2>=0`
`=>M(x)>=0`
Dấu "=" xảy ra khi `x=1`
`j)N(x)=4x^2-3x-7`
`=(2x)^2-2*2x*3/4+9/16-7-9/16`
`=(2x-3/4)^2-121/16>=-121/16`
Dấu "=" xảy ra khi `2x=3/4<=>x=3/8`
`k)P(x)=7x^2-2x-9`
`=7(x^2-2/7x)-9`
`=7(x^2-2*x*1/7+1/49-1/49)-9`
`=7(x-1/7)^2-9-1/7`
`=7(x-1/7)^2-64/7>=-64/7`
Dấu "=" xảy ra khi `x=1/7`
`l)Q(x)=5x^2-11x+6`
`=5(x^2-11/5x)+6`
`=5(x^2-2*x*11/10+121/100-121/100)+6`
`=5(x-11/10)^2-605/100+6`
`=5(x-11/10)^2-1/20>=-1/20`
Dấu "=" xảy ra khi `x=11/10`.
