1-8 The important point here is not the formula nor the mathematics. In fact, you may never have to compute a resonant frequency. The important point is for you to see that any given combination of L and C can be resonant at only one frequency; in this case, 205 kHz. The universal reactance curves of figures 1-2 and 1-3 are joined in figure 1-5 to show the relative values of X_{L} and X_{L} at resonance, below resonance, and above resonance.