Logarithmic Differentiation for (1+x)^(1/x): Finding dy/dx

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Logarithmic differentiation is applied to find dy/dx for y=(1+x)^(1/x) by taking the natural logarithm of both sides. This leads to the equation ln y = (1/x) ln(1+x). The derivative is expressed as (dy/dx)/y = (-1/x^2)(ln(1+x) + (1/x)(1/(1+x))). The final result for dy/dx can be simplified to y multiplied by the expression (-1/x^2)(ln(1+x) + x/(1+x)). The solution process and calculations need verification for correctness.
chapsticks
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Homework Statement



Use logarithmic differentiation to find dy/dx for y=(1+x)^(1/x).

Homework Equations


dy/dx


The Attempt at a Solution


ln y = ln (1+x)^(1/x)
= (1/x) ln (1+x)
(dy/dx) /y = (-1/x^2)(ln(1+x) + (1/x)(1/(1+x)

dy/dx = y [(-1/x^2) ( ln(1+x) + x/(1+x) ]
or (-1/x^2)( ln(1+x) + x/(1+x) ) (1+x)^(1/x)
 
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chapsticks said:

Homework Statement



Use logarithmic differentiation to find dy/dx for y=(1+x)^(1/x).

Homework Equations


dy/dx


The Attempt at a Solution


ln y = ln (1+x)^(1/x)
= (1/x) ln (1+x)
(dy/dx) /y = (-1/x^2)(ln(1+x) + (1/x)(1/(1+x)

dy/dx = y [(-1/x^2) ( ln(1+x) + x/(1+x) ]
or (-1/x^2)( ln(1+x) + x/(1+x) ) (1+x)^(1/x)

Do you have a question?
 
Yes, I want to check my work if it's correct.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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