Is the Derivative of y=x^(1/x) Correct?

  • Thread starter dylanhouse
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In summary, to find the derivative of y=x^(1/x), we use the chain rule and logarithmic differentiation. We first take the natural logarithm of both sides, then apply the chain rule to simplify the expression. After differentiating both sides, we can solve for y' and simplify the final result to y'=y(1-lnx/x^2).
  • #1
dylanhouse
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Homework Statement



Find the derivative of y=x1/x

Homework Equations



Chain rule and logarithmic differentiation.

The Attempt at a Solution



y=x^(1/x)
lny=lnx^(1/x)
lny=(1/x)lnx
(1/y)y'=(1/x)lnx
y'=y((1/x)lnx)
y'=y((1/x)(1/x)+(lnx)(1/x))
y'=y((1/x^2)+(lnx/x))
y'=x^(1/x)((1/x^2)+(lnx/x))

Sorry for all the brackets, and if they are not correct :$
 
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  • #2
In your 6th line I think I see a mistake you're using the product rule it seems? In the second part what did you take the derivative of?
 
  • #3
Should it read:

y'=y((1/x)(1/x)+lnx(1/x^2))?
 
  • #4
close shouldn't the derivative of x^-1 be -1*x^-2??
 
  • #5
So,
y'=y((1/x)(1/x)+lnx(-1/x^2))
y'=y((1/x^2)-(lnx/x^2))
y'=y(1-lnx/x^2)
 
  • #6
Looks good to me. Just plug in y like you did in the last step of the 1st post and you're golden.
 
  • #7
Thanks a bunch :)
 
  • #8
You have a problem with parentheses, but more importantly, lines 4 and 5 are very wrong.

You cannot differentiate the LHS and still equate it with the RHS without differentiating the RHS also.

However you still got there - as long as you correct your parentheses.
 
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Related to Is the Derivative of y=x^(1/x) Correct?

1. What is a derivative?

A derivative is a mathematical concept that represents the rate of change of one variable with respect to another. In other words, it measures how much one quantity changes in relation to another quantity.

2. How do you calculate a derivative?

To calculate a derivative, you need to use calculus techniques such as the power rule, product rule, quotient rule, or chain rule. These rules involve taking the limit of a function as the change in the independent variable approaches zero.

3. Why is it important to check if a derivative is correct?

It is important to check if a derivative is correct because it is a crucial step in solving mathematical problems involving rates of change, optimization, and curve sketching. An incorrect derivative can lead to incorrect solutions and misunderstandings of the underlying concepts.

4. What are common mistakes when calculating derivatives?

Common mistakes when calculating derivatives include incorrect application of the rules, algebraic errors, and forgetting to take the limit. It is also important to pay attention to the domain and differentiability of the function when calculating derivatives.

5. How can I check if a derivative is correct?

To check if a derivative is correct, you can use algebraic simplification, graphing, or numerical methods such as approximation or differentiation by finite differences. It is also helpful to compare your result to known derivatives and double-check your work for any potential mistakes.

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