Derivative with Absolute Value

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Homework Help Overview

The problem involves finding the derivative of a function defined as f(x) = [x^2 * (3x + 2)^(1/3)] / [(2x - 3)^3], which is enclosed within absolute value symbols. The discussion centers around the implications of the absolute value on the differentiation process.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the need to account for the absolute value in the function when taking the derivative. There are mentions of using the quotient rule, product rule, and chain rule, but uncertainty remains about how to properly incorporate the absolute value. One participant suggests analyzing the function over different intervals to handle the absolute values appropriately.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the function due to the absolute value. Some guidance has been offered regarding interval analysis, but no consensus has been reached on a definitive approach. One participant expresses a desire to seek further clarification from an instructor.

Contextual Notes

There is a noted concern about the impact of the absolute value on the derivative, and participants are considering how to approach the problem given the constraints of the homework assignment.

science.girl
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Homework Statement


Find f'(x), if

f(x) = [x^2 * (3x + 2)^(1/3)] / [(2x - 3)3]

Where the absolute value symbol surrounds the entire function.

Homework Equations


N/A

The Attempt at a Solution


My attempts don't account for the absolute value of the function. Otherwise, I can still take the derivative using quotient rule, product rule, and chain rule. Must I approach things differently because of the absolute value symbols? If so, how?
 
Last edited:
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Is this your function?
\frac{|x^2(3x + 2)^{1/3}|}{(2x - 3)^3}

If so, you can simplify it a bit to this:
\frac{x^2|(3x + 2)^{1/3}|}{(2x - 3)^3}

You will need to take into account the absolute values of the factor in the numerator and the one in the denominator. One way to do this is to look at your function on three different intervals: -infinity < x <-2/3, -2/3 < x < 3/2, and 3/2 < x < infinity.
Each of these intervals gives a different version of your function if you remove the absolute values, so each will give you a different version of the derivative.
 
science.girl said:

Homework Statement


Find f'(x), if

f(x) = [x^2 * (3x + 2)^(1/3)] / [(2x - 3)3]
?


\frac{x^2}{(-3+2 x)^3 (2+3 x)^{2/3}}-\frac{6 x^2 (2+3 x)^{1/3}}{(-3+2 x)^4}+\frac{2 x (2+3 x)^{1/3}}{(-3+2 x)^3}

x^2/((-3 + 2 x)^3 (2 + 3 x)^(2/3)) - (
6 x^2 (2 + 3 x)^(1/3))/(-3 + 2 x)^4 + (
2 x (2 + 3 x)^(1/3))/(-3 + 2 x)^3

science.girl said:

Homework Equations


N/A

?

science.girl said:

The Attempt at a Solution


My attempts don't account for the absolute value of the function. Otherwise, I can still take the derivative using quotient rule, product rule, and chain rule. Must I approach things differently because of the absolute value symbols? If so, how?
 
You can also use the chain rule knowing that |x| = √(x2)
 
Ok; I think I understand how to approach this now. I'll get more help from my instructor to be sure. (I completed the assignment before, but wanted to understand for the final.)

So, thanks!
 

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