  We calculate $\partial\mu/\partial n$ in extrinsic graphene as a function of
carrier density $n$ at zero temperature by obtaining the electronic self-energy
within the Hartree-Fock approximation. The exchange-driven Dirac-point
logarithmic singularity in the quasiparticle velocity of intrinsic graphene
disappears in the extrinsic case. The calculated renormalized
$\partial\mu/\partial n$ in extrinsic graphene has the same qualitative
$n^{-\frac12}$ density dependence as the inverse bare density of states with a
20% enhancement from the corresponding bare value, a relatively weak effect
compared to the corresponding parabolic-band case.
