$\begin{array}{l} {x^3} + 5{x^2} + 6x\\  = x({x^2} + 5x + 6)\\  = x({x^2} + 2x + 3x + 6)\\  = x{\rm{[}}x(x + 2) + 3(x + 2){\rm{]}}\\  = x(x + 2)(x + 3) \end{array}$

$\begin{array}{l} {x^3} + 5{x^2} + 6x\\  = x({x^2} + 5x + 6)\\  = x({x^2} + 2x + 3x + 6)\\  = x{\rm{[}}x(x + 2) + 3(x + 2){\rm{]}}\\  = x(x + 2)(x + 3) \end{array}$

Chúc bạn học tốt

x 3 + 5 x 2 + 6 x x3+5x2+6x

= x 3 + 2 x 2 + 3 x 2 + 6 x x3+2x2+3x2+6x

= ( x 3 + 2 x 2 ) + ( 3 x 2 + 6 x ) (x3+2x2)+(3x2+6x)

= x 2 ( x + 2 ) + 3 x ( x + 2 ) x2(x+2)+3x(x+2)

= ( x 2 + 3 x ) ( x + 2 ) (x2+3x)(x+2)