`G=3x^2-5x+5=3x^2-5x+25/12+35/12=(x√3+5/(2√3))^2+35/12≥35/12`
Dấu `=` xảy ra `↔x√3+5/(2√3)=0↔x√3=-5/(2√3)↔x=-5/6`
Vậy `G_(min)=35/12↔x=-5/6`
`K=4x^2+3x+2=4x^2+3x+9/16+23/16=(2x+3/4)^2+23/16≥23/16`
Dấu `=` xảy ra `↔2x-3/4=0↔2x=3/4↔x=3/8`
Vậy `K_(min)=23/16↔x=3/8`
`N=2x^2+3x+4=2x^2+3x+9/8+23/8=(x√2+3/(2√2))^2+23/8≥23/8`
Dấu `=` xả ra `↔x√2+3/(2√2)=0↔x√2=-3/(2√2)↔x=-3/4`
Vậy `N_(min)=23/8↔x=-3/4`
