Let p = mv/sqrt(1-v^2/c^2)

dp/dt : correct syntax.
d/dt(p) : incorrect syntax.
Only a numbskull like Bonehead Green would write d/dt(p).
Come back Sept 21 when you realise you've fucked up, you clueless bastard.
According to Bonehead, force increases with velocity (the Einstein Expansion
that the fuckwit calls "Lorentz contraction").