# Doubt from limits

You cant subtract infinity from infinity. Its undefined

Then in the same way we canâ€™t cancel x terms in questions where we take some power of x commonâ€¦ Because that is always infinity / infinity form right??

Sorryâ€¦ Not exactly cancelâ€¦ But we divide x^2 or something in those questions where we use expansions of sinx, tanx etcâ€¦

So how can we divide by infinity?

It is something like this in the bookâ€¦

And

*this type of problems*as in given as an example below itâ€¦

And i have one more doubtâ€¦

How do i know whether to use sandwich theorem or the method in which we convert a summation to integralâ€¦??

Dont know bro. We seemingly cancel it algebraically.

Practice 4-5 questions of sandwich theorem and you will realise it yourself

Ohkâ€¦ Can you ask your sir?

Okayâ€¦ Thank you

practice a lot of questions bro after a certain period youâ€™ll just know which method to do just by scanning the question

Ok broâ€¦ Thanksâ€¦