ok ive read a bit on audio feedback, and have learned if the frequency that comes out of a load speaker is equal to the resonating frequency of the amplifier then that sharp high pitch noise is generated, now i will use a notch filter to stop that noise from being generated( in other words attenuate the signal at that frequency). which component resonant frequency must i determine (the frequency that must be attenuated) of the circuit? and how will i do that, is there a mathematical way?

 

It is not the resonate frequency of the amplifier, it is the whole system. This frequency can change as the mike is moved or people move around within the acoustic space. Also tone controls and your filter. Might work in some given circumstances.