(x-1)(x2-9)+x+3=0
<=>(x-1)(x-3)(x+3)+(x+3)=0
<=>(x+3)[(x-1)(x-3)+1]=0
<=>(x+3)(x2-4x+4)=0
<=>(x+3)(x-2)2=0
=> x=-3 hoặc x=2
(x - 1)(x^2 - 9) + x + 3 = 0
<=> x^3 - 9x - x^2 + 9 + x + 3 = 0
<=> x^3 - 8x - x^2 + 12 = 0
<=> (x^2 + x - 6)(x - 2) = 0
<=> (x - 2)(x + 3)(x - 2) = 0
<=> x - 2 = 0 hoặc x + 3 = 0
<=> x = 2 hoặc x = -3