A low-pass filter is to be designed to pass frequencies in the 0 to 12 kHz range. The gain of the amplifier is to be +10 at the low frequency and change by no more than 10 percent over the frequency range. In addition, the gain of the amplifier for frequencies greater than 14 kHz is to be no greater than 0.1. Determine f3-dB and the number of poles required in a Butterworth filter.