2(2x+1)+18=3(x+2)(2x+k)
Vì mình ko bt k là gì nên mình xin dc bỏ k đi
2(2x+1)+18=3(x+2).2x
(=)4x+2+18=6x(x+2)
(=)4x+30=6x²+12x
(=)4x+30-6x²-12x=0
(=)-6x²-8x+30=0
(=)-6x²+10x-18x+30=0
(=)-2x(3x-5)-6(3x-5)=0
(=)(-2x-6)(3x-5)=0
(=)\(\left[ \begin{array}{l}-2x-6=0\\3x-5=0\end{array} \right.\) (=)\(\left[ \begin{array}{l}-2x=6\\3x=5\end{array} \right.\) (=)\(\left[ \begin{array}{l}x=-3\\x=\frac{5}{3}\end{array} \right.\)
S={-3;$\frac{5}{3}$ }
