# Velocity proportional to wavelength?

There are two equations I know of that link velocity and wavelength:

1 velocity = frequency x wavelength

2 de broglie wavelength= planck's constant/ (mass x velocity)

I read that 'When particles are accelerated to high velocities, they have low wavelengths'.
This means that velocity has to be inversely proportional to wavelength, and this would come from the second equation. But why?

Thanks :)