  The number of events suitable for a determination of the gluon distribution
function g(x,Q^2) in a proton at the LHC for various intervals of x and Q^2 are
estimated. The contributions of main background sources to ``direct
photon+jet'' production processes are studied. The values of discrimination
powers between quark and gluon jets as well as between a single photon and the
products of pi^0, eta, K^0_s mesons decaying through the neutral channels are
applied to estimate the final contributions of various event types to the
"photon+jet" production in different intervals of x and Q^2. Monte Carlo events
generated by help of the PYTHIA 6.1 generator are used for this analysis.
