Question

a) ( 3 + x ) ( x ^ 2 - 9 ) - ( x - 3 ) ( x ^ 2 + 3x + 9 )

b) ( x + 6 ) ^ 2 - 2 x ( x + 6 ) + ( x - 6 ) ( x +6 )

Answer 1

a) (x-3).((3+x)²-(x²+3x+9))

<=> (x-3).(3x+9)

<=> 3.(x-3)²

Answer 2

a) đa thức

\(=\left(x-3\right)\left(x+3\right)^2-\left(x-3\right)\left(x^2+3x+9\right)=\left(x-3\right)\left(x^2+6x+9-x^2-3x-9\right)=3x\left(x-3\right)=3x^2-9x\)

b) đa thức \(=\left(x+6\right)^2-2x\left(x+6\right)+x^2-36=\left(x+6-x\right)^2-36=0\)