Đáp án:
a, $3x^{2}$ - 6x - x + 2 = 0
→ 3x × ( x - 2 ) + ( x - 2 ) = 0
→ ( x - 2 ) × ( 3x + 1 ) = 0
--> $\left \{ {{x - 2 = 0} \atop {3x + 1 = 0}} \right.$
--> $\left \{ {{x = 2} \atop {x = $\frac{-1}{3}$ }} \right.$
b,
$x^{4}$ - x - 4x + 4 = 0
--> x × ( $x^{3}$ - 1 ) - 4 × ( x - 1 ) = 0
--> x × ( x - 1 ) × ( $x^{2}$ - x + 1 ) - 4 × ( x - 1 ) = 0
--> ( x - 1 ) × ( $x^{3}$ - $x^{2}$ + x - 4 ) = 0
--> Bn tự lm tiếp nhé ( Giống như câu a ấy )