Limits

In (B) I've attached my solution and the solution given What's wrong with my solution?
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40 Replies
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coolguy.
coolguy.3mo ago
So there's a specific formula for these types of limits
coolguy.
coolguy.3mo ago
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coolguy.
coolguy.3mo ago
Yours is wrong because you assume the thing inside bracket to be exactly 1
Fusion
FusionOP3mo ago
O I see How would I derive this?
coolguy.
coolguy.3mo ago
When it's actually tending to 1 Usually you've to memorize this
Fusion
FusionOP3mo ago
The limit function is applied so can't I write it as 1
coolguy.
coolguy.3mo ago
Yes it's not 'exactly' 1
Fusion
FusionOP3mo ago
O ye I see now Alr thanks
coolguy.
coolguy.3mo ago
Np
Fusion
FusionOP3mo ago
Wdym by types Is this only applicable for 0^infinity type forms?
coolguy.
coolguy.3mo ago
Check in your textbook Also opt I'm kinda confused in this shouldn't it be 1+f(x) where f(x) tends to zero, But here even the cos fn is tending to 1 and not exactly 1
Opt
Opt3mo ago
@Fusion For $1^\infty$ type limits, try using this. $lim{x\to a} f(x)^{g(x)} = e^{lim{x\to a} g(x)\cdot(f(x)-1)}$ When we have f,g such that $f(x) \to 1, g(x) \to \infty$ as $x\to a$
TeXit
TeXit3mo ago
Opt
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coolguy.
coolguy.3mo ago
Okay yeah we gotta use this Mb fusion
Fusion
FusionOP3mo ago
The book has used the formula coolguy mentioned
coolguy.
coolguy.3mo ago
Yeah don't use the one I said that is a different form
Fusion
FusionOP3mo ago
How is your formula incorrect That's the one that the book uses though
Opt
Opt3mo ago
It's the same formula
coolguy.
coolguy.3mo ago
Different format
Fusion
FusionOP3mo ago
How would I derive this @Opt I'm wildly confused
Opt
Opt3mo ago
I forgot ngl. I remember reading this in some random book and it was useful I was never taught the derivation
Fusion
FusionOP3mo ago
I watched some lectures on limits and I'm still confused on the problem solving part I see
Opt
Opt3mo ago
I remember the derivation for 0^∞
coolguy.
coolguy.3mo ago
Just do mains pyq and remember diff formats
Opt
Opt3mo ago
That's just taking log and exponentiating simultaneously
Fusion
FusionOP3mo ago
Alr Do you have a formula sheet for formulae like this? Because these aren't in arihant (the book I'm using)
coolguy.
coolguy.3mo ago
Arihant is a great book it must have
Fusion
FusionOP3mo ago
It doesn't have these formulae though
coolguy.
coolguy.3mo ago
Lemme chk
Fusion
FusionOP3mo ago
It isn't under the limits chapter and functions chapter atleast Only expansion formulae are given
coolguy.
coolguy.3mo ago
And tbh you can note these formulae as you study in a diff nb, there aren't a while lot Right
Fusion
FusionOP3mo ago
Oh alr I'll do that then Thanks again
coolguy.
coolguy.3mo ago
Anytime
SirLancelotDuLac
The formula occurs as follows (1+f(x))^g(x) as f tends to zero and g tends to infinity, limits to e^f(x).g(x) (This occurs due to taylor expansion of (1+ax)^bx) Oh wait, I pinged the wrong person @Fusion
Fusion
FusionOP3mo ago
Thanks
SirLancelotDuLac
Welcome 🖖
Fusion
FusionOP3mo ago
+solved @coolguy. @Opt @SirLancelotDuLac
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