Bài 7:
Để `d` đi qua `A(1;3)` thì:
`3=a+b`
`=>b=3-a`
Để `d` đi qua `B(-3;-1)` thì:
`-1=-3a+b`
`=>-3a+3-a=-1`
`=>-4a=-4`
`=>a=1`
`b=3-1=2`
Vậy `a=1; b=2`
\(\left(d\right):y=x+m\)
1) \(A\left(1;2003\right)\in\left(d\right)\Leftrightarrow2003=1+m\)
\(\Leftrightarrow m=2002\)
2) \(x-y+3=0\)
\(\Leftrightarrow y=x+3\)
\(\left(d\right)//\left(y=x+3\right)\)
\(\Leftrightarrow\left\{{}\begin{matrix}1=1\left(đúng\right)\\m\ne3\end{matrix}\right.\)
\(\Leftrightarrow m\ne3\)