Derivative with Absolute Value

science.girl
Messages
103
Reaction score
0

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:
Physics news on Phys.org
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!
 
Thread 'Use greedy vertex coloring algorithm to prove the upper bound of χ'
Hi! I am struggling with the exercise I mentioned under "Homework statement". The exercise is about a specific "greedy vertex coloring algorithm". One definition (which matches what my book uses) can be found here: https://people.cs.uchicago.edu/~laci/HANDOUTS/greedycoloring.pdf Here is also a screenshot of the relevant parts of the linked PDF, i.e. the def. of the algorithm: Sadly I don't have much to show as far as a solution attempt goes, as I am stuck on how to proceed. I thought...

Similar threads

Replies
25
Views
2K
Replies
16
Views
2K
Replies
3
Views
1K
Replies
1
Views
1K
Replies
4
Views
2K
Replies
4
Views
2K
Back
Top