A boat moves north at a constant speed. A second boat, moving at the same speed, pursues the first boat in such a way that it always points directly at the first boat. When the first boat is at the point (0, 1), the second boat is at the point (6, 2.5), with the positive y-axis pointing north. It can then be shown that the curve traced by the second boat, known as a pursuit curve, is given by

Find the y-coordinate of the southernmost point of the second boat’s path.

y x 16 - 2 lnx + 1 4 + 2 ln 6.