Sunday, November 1, 2015

f(x)=(x+1)^1/x. Calculate lim f(x); x->infinity.

f(x)=(x+1)^1/x.


Calculate lim f(x); x->infinity.


`lim_(x->oo) (x+1)^(1/x)`


` `This is in the indeterminate form infinity raised to zero. To find the limit we need to rewrite it into a from so that we can use L'Hopital's rule. 


Lets say that this limit is equal to L. Take the natural log of both sides: 


ln(L) = (1/x) ln(x +1)


Focusing only on the right side we get: 


`lim_(x->oo) ln(x+1)/(x)`


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` `Now we're in an infinity / infinity form and can use L'Hopital's rule. 


Take the derivative of the numerator and denominator to get: 


`lim_(x->oo) ((1)/(x+1))/(1)`


This limit is equal to 0. 


But we're not done yet!


Keep in mind that the original limit we're solving for is L. This 0 is actually ln(L). To solve for L, we need to undo the logarithm by using e. 


So L = e^0 = 1. 

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