`x^2 - 4 = (x + 2)(3x - 1)`
`⇔ x^2−4=3x^2+5x−2`
`⇔ x^2−4−3x^2=5x−2`
`⇔ −2x^2−4=5x−2`
`⇔ −2x^2−4−5x=−2`
`⇔ −2x^2−4−5x+2=0`
`⇔ −2x^2−2−5x=0`
`⇔ −2x^2−5x−2=0`
`⇔` \(\left[ \begin{array}{l}a + b =-5\\ab=-2(-2)=4\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}-1,-4\\-2,-2\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}-1-4=-5\\-2-2=-4\end{array} \right.\)
`⇔ (−2x^2−x)+(−4x−2)`
`⇔ −x(2x+1)−2(2x+1)`
`⇔ (2x+1)(−x−2)`
\(\left[ \begin{array}{l}x=-{ \dfrac{1}{2}}\\x=-2\end{array} \right.\)
Cho mình xin hay nhất nha bạn!!!!!
@Drew Mclntyre
