d đi qua \(I\left(-1;2\right)\) và \(\perp d':2x-y+4=0\)
\(\overrightarrow{n_{d'}}=\left(2;-1\right)\Rightarrow\overrightarrow{u_{d'}}=\left(-1;-2\right)=\overrightarrow{n_d}\)
\(\Rightarrow d:-1\left(-1\right)-2\left(2\right)+c=0=>c=3\)
d: x+2y-3 =0