Logarithmic Derivative of y = 5ln(7lnx)

In summary, the derivative of y = 5ln(7lnx) is y' = 5/(x ln(x)) or 35/(x ln(x)) after simplification. The original attempt at a solution did not consider the chain rule and included some incorrect terms.
  • #1
Jan Hill
63
0

Homework Statement



y = 5ln(7lnx)

Homework Equations



y' = 5 x 1/7lnx +97lnx0 x 1/x

= 5(7lnx)/7lnx + 5ln x 7/x


The Attempt at a Solution



y' = 5 + 35ln/x

is this right?
 
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  • #2
Jan Hill said:

Homework Statement



y = 5ln(7lnx)

Homework Equations



y' = 5 x 1/7lnx +97lnx0 x 1/x

= 5(7lnx)/7lnx + 5ln x 7/x
You're completely forgetting the chain rule.
Where did the 97 come from?
What does lnx0 mean?

y' = 5 * 1/(7 lnx) * d/dx(7 lnx) = ?
Jan Hill said:

The Attempt at a Solution



y' = 5 + 35ln/x

is this right?
 
  • #3
then I guess it should be

y' = 5/(7lnx) x 7/x

Y' = 35/x(7lnx)

Is that right?
 
  • #4
Jan Hill said:
then I guess it should be

y' = 5/(7lnx) x 7/x

Y' = 35/x(7lnx)

Is that right?
Yes, but it should be simplified to 5/(x ln(x))
 

Related to Logarithmic Derivative of y = 5ln(7lnx)

1. What is a logarithmic derivative?

A logarithmic derivative is a mathematical concept used to find the rate of change of a function that is defined in terms of logarithms. It is also known as the log-derivative or the logarithmic differentiation.

2. How is a logarithmic derivative calculated?

A logarithmic derivative is calculated by taking the derivative of the logarithm of a function and then multiplying it by the original function. This can be represented mathematically as (ln f(x))'.

3. What is the use of a logarithmic derivative?

A logarithmic derivative is useful in simplifying complex functions and in solving differential equations. It can also be used to find the relative rates of change between two functions.

4. Can a logarithmic derivative be negative?

Yes, a logarithmic derivative can be negative. This means that the original function is decreasing at a certain point. However, the value of the logarithmic derivative itself does not indicate the direction of the function, as it is dependent on the value of the original function.

5. Are there any real-life applications of logarithmic derivatives?

Yes, logarithmic derivatives have many real-life applications in fields such as physics, economics, and engineering. For example, they can be used to model population growth, economic growth, and radioactive decay.

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