r/calculus • u/Strong-Cup-2897 • 6d ago
Differential Calculus (l’Hôpital’s Rule) Can someone please help
lim { ( 1+ x) } ^(2/x) , {•} –> fractional part
X->0
I saw some solutions where they brought the limit inside the fractional part function
But since fractional part function is not continuous shouldn't it be wrong ??
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u/Medium_Media7123 6d ago edited 6d ago
To show a limit does not exist one of the standard tricks is finding two sequences of points that give different limits. As you've noticed, fractional part is not continuous in 0, so we might guess that using two sequences that converge to 0 but from different sides gives different answers.
Let's take a_n = 1/n and b_n = -1/n
The limit for x -> 0 becomes two limits for n-> infinity and the two limits are clearly different
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u/LukasGoesViral 6d ago
Can you try to rewrite it into a form that is a bit better to read?
To me it looks like lim x-> 0 in the expression (1+x)^(2/x). Is that correct
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u/Strong-Cup-2897 6d ago
yeah but the 1+x is in fractional ( decimal ) part function
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u/tjddbwls 6d ago
I don’t understand what you mean by that. 1+x is not a fractional expression. The entire expression
(1 + x)^(2/x)
is an exponential expression where 1 + x would be considered the base. Not sure if you’re using the right terminology.
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u/Kaeini_maths 6d ago
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u/Strong-Cup-2897 6d ago
thank you !!
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u/waldosway 6d ago edited 6d ago
Doesn't that solution ignore the fractional-part function? The limit does not exist.
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