How to start ???

# Thread to share Good Questions from Calculus which requires deep thinking

**Rohan_Shinde1**#269

You can view my solution here

https://brilliant.org/problems/hola-a-revisit-to-beta-gamma-and-digamma/?ref_id=1542951

**Sarvesh_Pnchl**#271

Rohan_Shinde1 can u list some methods like in this case gamma function .,(feymen integral trick)..and many more whichw can help in jee and not that of olympiad type ..

**Mayank_2019_1**#273

@Sarvesh_Pnchl It is wayyyyyy beyond the scope of JEE

@Rohan_Shinde1 @Naman I did it this way ... In the end that limit one is that correct ?

**Sarvesh_Pnchl**#275

In this video how sir solved by complex number or is it also some out of syllabus method..

**Rohan_Shinde1**#276

The video was quite short to notice but it seemed he used the Residue theorem(He evaluated the residue at i) around some contour but still it's quite shady. It would have been more clearer if the video was a bit longer.

And if he did use contour integration then it's also out of her syllabus

**Sarvesh_Pnchl**#277

Off topic question.this out of jee things was taught by your teacher at allen or u learned yourself through use of internet (curious to know) Rohan_Shinde1

**Siddhant_2019**#280

Please elaborate what method he used to get answer so quickly @Azimuddin_Sheikh

7k per month are they mad or what😅

**seshu_ram**#281

I too saw this ad. I know a bit of integration from 12th but idk what sir did. Btw off topic: Unacademy Plus costs 7000 rs per month🤣

**Azimuddin_2019**#282

@Siddhant_Mudholkar Bro I am not getting how they just use I and solve it seriously , I am thinking about contour integrals , but as MC sir did , is way out of my mind . I will tell whenever I got free time from boards preparation

**arush_2019**#283

@Siddhant_Mudholkar

I think sir is doing it to chech the option...

I think there would be some theorem which gives constant term when we put "i" ..

And the last part gives -π