Đáp án:
1,` (2x +1) . (x - 2) = 0`
`⇒` \(\left[ \begin{array}{l}2x + 1 = 0\\x-2 = 0\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}2x = 0 - 1\\x= 0+2\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}2x = -1\\x=2\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x = -1:2\\x=2\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x = -0,5\\x=2\end{array} \right.\)
Vậy `x = -0,5` hoặc `x = 2`
2,` (x - 3) . (x + 4) = 0`
`⇒` \(\left[ \begin{array}{l}x - 3 = 0\\x+4 = 0\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x = 0 + 3\\x = 0-4\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x = 3\\x = -4\end{array} \right.\)
Vậy `x = 3` hoặc `x = -4`
