a)x^3-4x^2+4x
=x(x^2-4x+4)
=x(x-2)^2
b)3x^2-3y^2-7x+7y
=3.(x-y)(x+y) -7(x-y)
=(x-y).(3x+3y-7)
c)2x^2-5x+3
=2x^2-2x-3x+3
=2x(x-1)-3(x-1)
=(x-1)(2x-3)
d)8x^3-27
=(2x)^3-27
=(2x-3)(4x^2+6x+9)
e)(x+2)(x+4)(x+6)(x+8)+16
=(x+2)(x+8)(x+4)(x+6)+16
=(x^2+8x+2x+16)(x^2+6x+4x+24)+16
=(x^2+10x+16)(x^2+10x+16+8)+16
Đặt x^2+10x+16=a
=>>x^2+10x+16+8=a+8
=a.(a+8)+16
=a^2 + 8a+16
=(a+4)^2
=(x^+10x+20)^2