Simple integral, textbook seems wrong

In summary, the conversation is about finding the equation of a curve with a given slope and point. The attempt at a solution involves integrating (ln x)^2 and solving for the constant. However, there is confusion regarding the factor of 2 in the integral and the final answer given in the textbook.
  • #1
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Homework Statement



Find the equation of the curve for which the slope is (ln x)^2/x and passes through P(1, 2)


Homework Equations





The Attempt at a Solution



Integrate (ln x)^2 = 1/2 Integral( ((ln x)^2) 2/x dx)

I get: 1/2 [((ln x)^3/3) + C]

Then solving for C, I get C=2

Then my final answer is (ln x)^3/6 + 2

The textbook says it is (ln x)^3/3 + 2.

I don't get it.
 
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  • #2
How exactly did you make this integration: Integral( ((ln x)^2) 2/x dx)
you should get out [tex]\frac{2ln(x)^3}{3}[/tex]
Why did you actually put this factor 2 in the integral and divide by 2 again, I don't get why this makes sense.
 
  • #3
Well I got [tex]\int \frac{(ln x)^2}{x} dx = \frac{1}{3} (ln x)^3 + C [/tex]. Don't see where you got that factor of 1/2 from. C = 2, so that's right.
 

Related to Simple integral, textbook seems wrong

1. Why does my textbook's answer to a simple integral seem incorrect?

Textbooks often use simplified versions of integrals to make them easier to solve, which can sometimes result in a different answer than the more complex integral you are trying to solve. It is important to carefully check your work and consider if there are any simplifications that can be made.

2. How can I check if my answer to a simple integral is correct?

You can use online integral calculators or software like Wolfram Alpha to check your answer. You can also use the fundamental theorem of calculus to take the derivative of your integral and see if it matches the original function.

3. Can I use different methods to solve a simple integral?

Yes, there are multiple methods for solving integrals, such as substitution, integration by parts, and trigonometric substitution. It is important to choose the method that works best for the integral you are trying to solve.

4. What should I do if I am still getting an incorrect answer for a simple integral?

If you are confident in your work and have checked it multiple times, it is possible that there is an error in the textbook's answer. You can consult with your teacher or a tutor for further clarification.

5. Why is it important to understand simple integrals?

Integrals are an essential concept in calculus and are used to solve a variety of real-world problems in fields such as physics, engineering, and economics. Understanding simple integrals is crucial for building a strong foundation in calculus and being able to apply it to more complex problems.

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