`a) (x - 4)(x - 4)^2 = 0`
`=> (x - 4)^(1 + 2) = 0`
`=> (x - 4)^3 = 0`
`=> x - 4 = 0`
`=> x = 4 `
Cách khác:
`a) (x - 4)(x - 4)^2 = 0`
`=>` \(\left[ \begin{array}{l}x-4=0\\(x-4)^2=0\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=4\\x=4\end{array} \right.\)
Vậy `x=4`