b: Thay x=-3 và y=0 vào (d), ta được:
-3m+6+3=0
hay m=3
\(a,m=4\Leftrightarrow y=2x+3\\ b,\Leftrightarrow A\left(-3;0\right)\in\left(d\right)\\ \Leftrightarrow3\left(2-m\right)+3=0\Leftrightarrow9-3m=0\Leftrightarrow m=3\\ c,\text{PT hoành độ giao điểm: }2x+3=x+3\Leftrightarrow x=0\Leftrightarrow y=3\Leftrightarrow C\left(0;3\right)\Leftrightarrow OC=3\\ \text{PT giao Ox: }\left\{{}\begin{matrix}\left(d\right):y=0\Leftrightarrow x=\dfrac{3}{2-m}\Leftrightarrow OA=\dfrac{3}{\left|m-2\right|}\\\left(d'\right):y=0\Leftrightarrow x=-3\Leftrightarrow OB=3\end{matrix}\right.\\ \Leftrightarrow AB=OB+OA=\dfrac{3}{\left|m-2\right|}+3\\ S_{ABC}=\dfrac{1}{2}OC\cdot AB=\dfrac{3}{2}\left(\dfrac{3}{\left|m-2\right|}+3\right)=3\\ \Leftrightarrow\dfrac{3}{\left|m-2\right|}+3=2\\ \Leftrightarrow\dfrac{3}{\left|m-2\right|}=-1\Leftrightarrow m\in\varnothing\left(\dfrac{3}{\left|m-2\right|}>0\right)\)
