Differentiate vx using product rule,
Put 1 – v2 = t hence differentiating with respect to v we get dt/dv = -2v which means 2vdv = -dt
Now it is given that the curve is passing through (2, 1)
Hence (2, 1) will satisfy the curve equation (a)
Putting values x = 2 and y = 1 in (a)
Put c in equation (a)
Using log a + log b = log ab