The circuit in the following figure utilizes an ideal op amp. Find I1, I2, I3, and Vx. If Vo is not to be lower than -13 V, find the maximum allowed value for Ri. If Ri is varied in the range 100 to 1 kΩ, what is the corresponding change in IL and in Vo?
10 kΩ
Vx
Ri
100 Ω
10 kΩ
Vo
1 V