4) The difference amplifier as shown in Fig. (8) was built using R1 = R3 = 1 kOhms, R= R4 = 2 kOhms, V1 = -3.00 V, and V2 = 2.00 V. The theoretical Vout was calculated using the following relationship, 
and the voltage measured came to, 
verifying that the circuit works as to be expected.