a: =>(x+1)(x^2-x+1)-(x+1)(x+4)=0
=>(x+1)(x^2-2x-3)=0
=>(x+1)^2(x-3)=0
=>x=3 hoặc x=-1
b: =>x(x-6)-2(x-6)=0
=>(x-6)(x-2)=0
=>x=6 hoặc x=2
`a, (x+1)(x^2-x+1) - (x+1)(x+4) = 0`
`<=> (x+1)(x^2 - x +1 - x - 4) = 0`
`<=> (x+1)(x^2- 2x - 3) =0
`<=> (x+1)(x-3)(x+1) = 0`
`<=>` \(\left[{}\begin{matrix}x=3\\x=-1\end{matrix}\right.\)
`b, x(x-6) - 2(x-6) = 0`
`<=> (x-2)(x-6) = 0`
`<=>` \(\left[{}\begin{matrix}x=2\\x=6\end{matrix}\right.\)