\(\omega_{1}\) is near \(30 \mathrm{rad} / \mathrm{s}\) and \(\omega_{2}\) is near \(60 \mathrm{rad} / \mathrm{s}\)

A DOF system with a cubic nonlinearity has a linear natural frequency of \(120 \mathrm{rad} / \mathrm{s}\). The system is forced by harmonic excitations at different frequencies \(\omega_{1}\) and \(\omega_{2}\). What resonances does the system have under the given circumstances.