A multistage amplifier has a low-pass response with three real poles at $s=-\omega_{1}-\omega_{2}$ and $\omega_{3}$. The approximate overall bandwidth $\mathrm{B}$ of the amplifier will be given by
- $\mathrm{B}=\omega_{1}+\omega_{2}+\omega_{3}$
- $\frac{1}{\mathrm{~B}}=\frac{1}{\omega_{1}}+\frac{1}{\omega_{2}}+\frac{1}{\omega_{3}}$
- $\mathrm{B}=\left(\omega_{1}+\omega_{2}+\omega_{3}\right)^{1 / 3}$
- $\mathrm{B}=\sqrt{\omega_{1}^{2}+\omega_{2}^{2}+\omega_{3}^{2}}$