VMP VMD contradiction? Please help!

[BEagle]

Sorry, my fat fingers. Conventionally it's actually D=AV² + B/V² (where AV² indicates the elements of drag which increase with speed² and B/V² indicates lift dependent drag which decreases with speed²)

If D=AV² + B/V²

Then dD/dV = 2AV - 2B/V³

At minimum, dD/dV = 0. Hence 2AV=2B/V³, in other words Vmd=(4th root) B/A

But P=D x V; i.e. P=AV³ + B/V

dP/dV = 3AV² - B/V²

Again, at minimum, dP/dV = 0. Hence 3AV²=B/V², in other words Vmp=(4th root) B/3A.

Thus comparing these results, Vmd/Vmp = (4th root) 3 = 1.32