Question

Find the equations of the straight lines parallel to the coordinate axes and passing through the point $(3,-4)$.

Answer 1

The equation of line parallel to $x$ is $y=k$
It passes through $(3,-4)$
$\Rightarrow k=-4$
$\therefore$ The equation of line parallel to $x$ axis is $y=-4$.
The equation of line parallel to $y$ axis is $x=k$.
It passes through $(3,-4)$
$\Rightarrow 3=k$
The equation of line parallel to $y$ axis is $x=3$.