Inductive Reactance, $X_{L_{p}}$
If we expand $X_{L_{p}}$ as, which was derived in the
topic
$$X_{L_{p}} = { R^2_l + X^2_L \over X_L } = { R^2_l (X_L) \over X_L(X_L) } + X_L\\
={ X_L \over Q^2_L } + X_L$$
then, for $Q_l \geq 10$, $X_L/Q_l^2 \appro 0$ compared to $X_L$ , and
$$X_{L_{p}} \appro X_L $$
and since resonance is defined by $X_{L_{p}} = X_C$, the resulting condition for resonance is reduced to:
$$ X_L \appro X_C \,\, \text{ (Ql>10)}$$