A=x(x + 4)(x + 6)(x + 10) + 128
A=(x^2 + 10x) (x^2 + 10x + 24) + 128
A=(x^2 +10x + 12 -12)(x^2 + 10x + 12 + 12) + 128
A=(x^2 +10x + 12) -12^2 + 128 = (x^2 + 10x + 12)^2 - 16
A=(x^2 +10x + 12 - 16)(x^2 + 10x + 12 + 16)
A=(x^2 +10x - 4)(x^2 + 10x + 28)
Chúc bạn học tốt !~