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This is the image of the question

I tried to solve this question by applying KCL at the first inverting node and then applied it to the 2nd inverting node.

The answer I got is \$V_o\$ = 66V, which is not possible, and for Point B = -20V.

I checked the formulas and I think my KCL is right. I am attaching a photo of my solution.

This is the image of the solution

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  • \$\begingroup\$ I get the same answer as you did (66V). The book is wrong. \$\endgroup\$ Commented Nov 20 at 13:38

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Answer D is definitely wrong. I used a simulator and got this: -

enter image description here

I get 66 volts on Vout.

As a matter of interest, I was in the process of simulating it so that I could demonstrate a different way of solving the problem without all the fuss of the two inverting nodes being connected by a resistor: -

enter image description here

It may look more complex but, it resolves each op-amp into separate (non-interlocked) circuits that can be solved individually as two summing amplifiers using conventional formulae.

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  • \$\begingroup\$ Thanks for verification \$\endgroup\$ Commented Nov 20 at 13:47
  • \$\begingroup\$ @KushalDubey as a new contributor please take note of the following: What should I do when someone answers my question. If you are still confused about something then leave a comment to request further clarification. \$\endgroup\$ Commented Nov 20 at 13:56
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    \$\begingroup\$ @ Andy aka - Congratulation! Redrawing the circuit (second picture) is a surprising simple method for solving the task based on well-known gain expressions. \$\endgroup\$ Commented Nov 20 at 14:09
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Your solution is correct. The typo is in the question that you have uploaded. If the answer has to be 6V, then, instead of 12V the offset will be 2V. You can try this falstad simulation and verify it yourself.

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