a) (x - 3)² < x² - 5x + 4
<=> x² - 6x + 9 < x² - 5x + 4
<=> x² - x² - 6x + 5x < 4 - 9
<=> -x = -5
<=> x = 5
Vậy x = 5
b) x² - 12x + 11 > 0
<=> x² - x - 11x + 11 > 0
<=> x(x - 1) - 11(x - 1) > 0
<=> (x - 1)(x - 11) > 0
<=>$\left \{ {{x - 1}> 0 \atop {x-11}>0} \right.$
<=> $\left \{ {{x }> 1 \atop {x}>11} \right.$
Vậy x ∈ { 1 ; 11}
Cho mk ctlhn và 5 sao nhé!!!!
