$OA=2OB\to |x_A|=2|y_B|$
$\to x_A=\pm 2y_B$
Với $m\ne 0$:
- Nếu $x_A=2y_B$
Gọi $B(0;m)$, $A(2m;0)$
$\to d: \dfrac{x}{2m}+\dfrac{y}{m}=1$
$\to \dfrac{2}{2m}+\dfrac{3}{m}=1$
$\to m=4$
Vậy $d: \dfrac{x}{8}+\dfrac{y}{4}=1$
- Nếu $x_A=-2y_B$
Gọi $B(0;-m)$, $A(2m; 0)$
$\to \dfrac{x}{2m}-\dfrac{y}{m}=1$
$\to \dfrac{2}{2m}-\dfrac{3}{m}=1$
$\to m=-2$
Vậy $d: \dfrac{-x}{4}+\dfrac{y}{2}=1$
