Goi $I$ la giao diem cua $d_1$ va $d_2$. Toa do diem $I$ la nghiem cua he:$\left\{ \begin{array}{l} y=3x-m-1\\ y=2x+m-1 \end{array} \right.$$\left\{ \begin{array}{l} x=2m\\ y=5m-1 \end{array} \right.$
vay $I$ luon nam tren duong thang $(d):\left\{ \begin{array}{l} x=2m\\ y=5m-1 \end{array} \right.$hay $(d):5x-2y-2=0$
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