The forced harmonic oscillations have equal displacement amplitudes at frequencies ω1=400 s−1\omega_{1}=400 \mathrm{~s}^{-1}ω1=400 s−1 and ω2=600 s−1\omega_{2}=600 \mathrm{~s}^{-1}ω2=600 s−1 Find the resonance frequency at which the displacement amplitude is maximum.