46. 如右圖所示之理想運算放大器電路 Vin1 = 1 V,Vin2 = 0.5 V,Vin3 = 2 V,R1 = 4 kΩ,R2 = 5 kΩ,R3 = 10 kΩ,Rf = 20kΩ,試求總輸出電壓 Vout約為何?(A) -3 V(B) -6 V(C) -8 V(D) -11 V