The derivative of the function for the given curve is the slope of the curve at any point.
The slope of the given line is 1/2; we want the slope of the normal to the curve to also be 1/2. That means we want the slope of the curve at that point to be -2.
The slope is 1/2; the point on the curve is (2,3). The equation of the normal is
A graph, showing the given curve (red), the given line (green), and the normal to the curve parallel to the given line (blue).