a) \(\hept{\begin{cases}x=1\\y=3\end{cases}\Rightarrow3=a.1\Rightarrow a=3}\)
b) B(xo,yo) thuộc y=3x=> yo=3.xo
\(p=\frac{x_o+1}{3x_o+3}=\frac{x_o+1}{3\left(x_o+1\right)}\)
\(\hept{\begin{cases}x_0=-1\Rightarrow P=kXD\\x_o\ne-1\Rightarrow P=\frac{1}{3}\end{cases}}\)