\(x^2+3x-18=0\)
\(\Leftrightarrow x^2-3x+6x-18=0\)
\(\Leftrightarrow x\left(x-3\right)+6\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(x+6\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x-3=0\\x+6=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=3\\x=-6\end{array}\right.\)
Vậy x=3;x=-6
x2+3x-18=0
=>x2-3x+6x-18=0
=>x(x-3)+6(x-3)=0
=>(x+6)(x-3)=0
=>x=-6 hoặc x=3
x2 + 3x -18=0
↔x2+ 6x -3x -18=0
↔ (x+6)x - 3(x+6)=0
↔(x+6)(x - 3)=0
↔x=3 hoac x= -6
X^2+6x-3x-18=0
(X^2+6x)-(3x+18)=0
X(x+6)-3(x+6)=0
(X+6).(x-3)=0
{(X+6)=0
{(X-3)=0
X=(-6)và3
