Is the derivative of (ln x)^2 a u-sub?

  • Thread starter amb1989
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In summary, the answer is not quite 1/(2x)^2. You may need to use a substitution or apply the product rule.
  • #1
amb1989
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Is this a u-sub? I went through and got 1/(2x)^2 but I am not sure if that is correct.
 
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  • #2
You can use a substitution, but the answer is not quite 1/(2x)^2.

How did you arrive at that answer?
 
  • #3
danago said:
You can use a substitution, but the answer is not quite 1/(2x)^2.

How did you arrive at that answer?

Actually I asked the wrong question.

I'm working on an integration by parts problem it asks me to integrate what is in the topic title.
I went about it by saying that U = ln(x)^2 and that dv = 1.

When I went through and plugged everything into the integration by parts formula I arrived at

xln(x)-(integral sign)(1)(1/(2x)^2)

The thing that I am getting hooked up is trying to take that integral of 1/(2x)^2. I think I messed up somewhere but I am not sure where to look. Any suggestions?
 
  • #4
Hmm I am not really sure how you ended up xln(x)-(integral sign)(1)(1/(2x)^2).

I would choose the same parts as you did, i.e. u = (ln x)^2 and dv = 1, but I am not sure you applied the formula correctly.

[tex]\int u dv =uv - \int v du[/tex]

Is that what you are using?
 
  • #5
danago said:
Hmm I am not really sure how you ended up xln(x)-(integral sign)(1)(1/(2x)^2).

I would choose the same parts as you did, i.e. u = (ln x)^2 and dv = 1, but I am not sure you applied the formula correctly.

[tex]\int u dv =uv - \int v du[/tex]

Is that what you are using?

Yeah that's what I am using. du = 1/(2x^2) v= x

(lnx)^2)(x)-(integral)(1/(2x)^2)(1)

Did I take the derivative of (ln(x))^2 wrong?
 
  • #6
Yea maybe have another look at the derivative of (ln x)2

You could use the substitution z = ln(x), or treat it as (ln x)2 = (ln x)(ln x) and apply the product rule.
 

FAQ: Is the derivative of (ln x)^2 a u-sub?

1. What is the derivative of (ln(x))^2?

The derivative of (ln(x))^2 is 2ln(x)/x.

2. How do you find the derivative of (ln(x))^2?

To find the derivative of (ln(x))^2, you can use the power rule and the chain rule. First, rewrite the expression as (ln(x))^2 = (ln(x))*(ln(x)). Then, using the power rule, the derivative is (ln(x))'*(ln(x)) + (ln(x))*(ln(x))' = 2ln(x)/x.

3. Why is the derivative of (ln(x))^2 2ln(x)/x?

The derivative of (ln(x))^2 is 2ln(x)/x because of the power rule and the chain rule. The power rule states that the derivative of x^n is nx^(n-1). And the chain rule states that the derivative of f(g(x)) is f'(g(x))*g'(x). Applying these rules to (ln(x))^2, we get 2ln(x)/x.

4. Can the derivative of (ln(x))^2 be simplified further?

Yes, the derivative of (ln(x))^2 can be simplified further. Using logarithm rules, we can rewrite 2ln(x)/x as 2ln(x^(1/x)) = 2(ln(x)/x)ln(x). This may be a more simplified form, depending on the context of the problem.

5. Are there any real-life applications of the derivative of (ln(x))^2?

Yes, there are many real-life applications of the derivative of (ln(x))^2. One example is in economics and business, where it can be used to calculate marginal cost and marginal revenue. It is also used in statistics and probability to calculate the probability density function of certain distributions. In physics, it is used to calculate rates of change in various systems.

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