>the framing as a resistor network since I think that should be linear transistors are essentially non-linear, but they amplify and can be made to amplify line

>the framing as a resistor network since I think that should be linear transistors are essentially non-linear, but they amplify and can be made to amplify linearly through the use of feedback resistors: if you divide the output voltage across a resistor pair which fixes the output as ratio to the input voltage, that geometric relationship will hold across broad range of input/outputs. for most applications you want linear amplification. (transistors work as a function of current, but passing the current through resistors yields a voltage measurement) a transistor can be thought of as resistive if you treat its voltage:current relationship as a measurement of resistance.