Answer
$x=2-2t, y=0, z=-4t$
Work Step by Step
Step 1. Identify the coordinates of the known points: $P(2,0,0)$ and $Q(0,0,-4)$
Step 2. Establish a vector along the line as: $\vec u=\vec {PQ}=\langle -2,0,-4 \rangle$
Step 3. Based on the general parametric equation of a line passing point P and parallel to vector $\vec u$, we have $x=2-2t, y=0, z=-4t$
