Bổ sung câu `b+c`
`b, x^3 - 4x^2 + 5x - 2 = 0`
`<=>(x^2-3x+2)(x-1)=0`
`<=>(x-2)(x-1)(x-1)=0`
`<=>x=2` hoặc `x=1`
`c,(x + 1)2(x + 2) + (x - 1)2(x - 2) = - 12`
`<=>2(x+1)(X+2)+(x-1)*2(x-2)=-12`
`<=>2x^2+4x+2x+4+2x^2-4x-2x+4=-12`
`<=>4x^2+8-12`
`<=>x^2=-5`
`<=>`Pt vô no.