Help with simple integration problem

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In summary, the integral of ln(x) is equal to xlnx-x dx, which can be used to solve the equation y'= Ln(12x). To solve this problem, we can use integration by parts by writing the integrand as 1.ln(x). This leads to the correct answer of xlnx+(ln(12)-1)x.
  • #1
CaityAnn
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Solve y'= Ln(12x)



Homework Equations


Integral of ln(x)= xlnx-x dx


The Attempt at a Solution


12x*ln(12x)-12x dx or even xlnx-x*1/12
But I am pretty sure these are wrong.

My calculator gives me xlnx+(ln(12)-1)x wth? Help!
 
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  • #2
do you know how to do integration by parts?
in order to solve this problem you need to use it.
 
  • #3
CaityAnn said:
Solve y'= Ln(12x)



Homework Equations


Integral of ln(x)= xlnx-x dx


The Attempt at a Solution


12x*ln(12x)-12x dx or even xlnx-x*1/12
But I am pretty sure these are wrong.
Yup, they are incorrect.

To do this, you should note why the integral of ln(x) is equal to xlnx-x dx. Namely, we use integration by parts, writing the integrand as 1.ln(x). So, for your question, we have [tex]\int \ln(12x) dx=\int 1\cdot\ln(12x) dx [/tex]. Now, can you see a suitable choice for "u" and "dv" to enable you to perform integration by parts on this?

My calculator gives me xlnx+(ln(12)-1)x wth?
Your calculator is correct. [When you have the answer, check to see if yours is the same as this]
 
  • #4
Try substituting 12x = u and work from there.

EDIT: Damn my slowness. And also cristo's method is better, mine is rather lazy.
 
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FAQ: Help with simple integration problem

What is a simple integration problem?

A simple integration problem is a mathematical question that involves finding the antiderivative or integral of a given function. It is used to calculate the area under a curve or to solve problems related to rates of change.

What are the steps to solve a simple integration problem?

The steps to solve a simple integration problem are:
1. Identify the function and its limits of integration.
2. Simplify the function if possible.
3. Use integration rules, such as the power rule, product rule, or chain rule to find the antiderivative.
4. Apply the limits of integration and solve for the final result.

What is the difference between definite and indefinite integration?

Definite integration involves finding the area under a curve between specific limits, while indefinite integration involves finding the general antiderivative of a function without any limits. In other words, definite integration gives a numerical value while indefinite integration gives a function.

What are some common integration rules?

Some common integration rules include the power rule, product rule, quotient rule, chain rule, and substitution rule. These rules help in finding the antiderivative of a given function.

How can I check my answer for a simple integration problem?

To check your answer for a simple integration problem, you can differentiate the antiderivative you found to see if it matches the original function. You can also use online integration calculators to verify your answer.

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