Answer: x = -3
Step-by-step explanation: If a line has an undefined slope, it means that the line is vertical. A vertical line is parallel to the y-axis and does not have a slope.
To find the equation of a vertical line, we need to know the x-coordinate of any point on the line. In this case, the point (-3,4) is given.
Since the line is vertical and parallel to the y-axis, the equation of the line will be in the form x = constant, where the constant is the x-coordinate of the given point.
Therefore, the equation of the line that passes through the point (-3,4) and has an undefined slope is x = -3.