equation: $x=0$ Refer to the image below for the graph.
Work Step by Step
RECALL: A line with an undefined slope is vertical and has an equation of the form $x=h$ where $h$ is the x-intercept. Plot the point $P(0, 3)$. The line has an undefined slope, so it is vertical. Points on a vertical line share the same x-value. Thus, plot any point with same x-value as $P$, then connect the points using a straight line to complete the graph. (refer to the image below for the graph). The equation of the line is $x=0$.