Derivative with Absolute Value

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To find the derivative of the function f(x) = |[x^2 * (3x + 2)^(1/3)] / [(2x - 3)^3]|, it is essential to consider the absolute value, which affects the function's behavior across different intervals. The derivative can be computed using the quotient rule, product rule, and chain rule, but the absolute value necessitates analyzing the function in three distinct intervals: (-∞, -2/3), (-2/3, 3/2), and (3/2, ∞). Each interval will yield a different version of the function without absolute values, leading to varying derivatives. Understanding how to incorporate the absolute value into the derivative calculation is crucial for accuracy. Seeking further clarification from an instructor is recommended to solidify this understanding.
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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?
 
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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!
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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