Transfer Function for a Non-Inverting Op-Amp with Feedback
The transfer function of this cicuit



is simply Vo = Vin.

R1 is connected between the opamp output and ground.  It loads the opamp, but doesn't have any effect on the output voltage.  The - input is driven from the output via R2.  Since this is a ideal opamp, which therefore has infinite input impedance, there is no current thru R2 and therefore no voltage across it.

I suspect this drawing is a mistake, with R1 intended to be between the - input and ground.