Finding error in circuit analysis solution

[Sanosuke Sagara]

I have my solution and mt doubt in the attachment that followed and I hope that somebody will help me figure out.Thanks for anybody that spend some time on this question.

 

[Curious3141]

This is sort of a trick question, because it's really very easy.

Ask yourself : is there any feedback in this circuit ? Feedback is when the output is fed back in part to the input. Does it happen here ?

What happens when there is no feedback in an opamp ? Hint : Comparator. Look this term up.

Find the voltage at the negative input. Hint : Voltage divider. Is it different from that at the positive input ?

What happens to the output ? Hint : Saturation.

 

[Sanosuke Sagara]

Thanks for your hint and help ,and I will try to figure out this question by myself.