Look at fig 13-5-12

This is a power required curve. The point at the bottom of the curve is Vmp.

The velocity for minimum power.

It is the minimum speed for straight and level flight.

The tangent to the curve, shown as Vx in this diagram is Vmd. (This can be proved). So Vmp is less than Vmd .

Because it is proportional to Vmd it is always less.