How to Find Extrema, Roots, Inflection Points, and Concavity Using Derivatives?

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In summary, the conversation is about finding extrema, roots, inflection points, and concavity using the first and second derivative tests for the equation y=3(x-1)^{\frac{1}{3}}-(x-1)^{2}. The attempt at a solution involves finding the first derivative and simplifying it, but there is a mistake in the simplification. The person needs help identifying extrema and determining if they made a mistake in the algebra.
  • #1
crybllrd
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Homework Statement



[itex]y=3(x-1)^{\frac{1}{3}}-(x-1)^{2}[/itex]

I need to find all extrema, roots, inflection points, and concavity using first and second derivative tests.
I usually do not have a problem with these, but I need to find some extrema that I know exist.

The Attempt at a Solution



[itex]y'=2(x-1)^{\frac{-1}{3}}-2(x-1)[/itex]

simplified to:

[itex]y'=\frac{2+(-2x+2)(x-1)^{\frac{1}{3}}}{(x-1)^{\frac{1}{3}}}[/itex]

From looking at a graph I can see that there are extrema at x=0, and x=2. There is also a sharp turn at (1,0). However, i am not seeing these extrema in my first derivative. Did I not simplify enough or make an algebraic error?
 
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  • #2
crybllrd said:

Homework Statement



[itex]y=3(x-1)^{\frac{1}{3}}-(x-1)^{2}[/itex]

I need to find all extrema, roots, inflection points, and concavity using first and second derivative tests.
I usually do not have a problem with these, but I need to find some extrema that I know exist.

The Attempt at a Solution



[itex]y'=2(x-1)^{\frac{-1}{3}}-2(x-1)[/itex]
There's a mistake in the above.
d/dx(3(x - 1)^(1/3)) = (x - 1)^(-2/3)
crybllrd said:
simplified to:

[itex]y'=\frac{2+(-2x+2)(x-1)^{\frac{1}{3}}}{(x-1)^{\frac{1}{3}}}[/itex]

From looking at a graph I can see that there are extrema at x=0, and x=2. There is also a sharp turn at (1,0). However, i am not seeing these extrema in my first derivative. Did I not simplify enough or make an algebraic error?
 
  • #3
Thanks, I'm not sure how I missed that. I can take it from here.
Thanks again
 

Related to How to Find Extrema, Roots, Inflection Points, and Concavity Using Derivatives?

1. What is derivative simplification?

Derivative simplification is the process of reducing a derivative to its simplest form by using algebraic rules and properties.

2. Why is derivative simplification important?

Derivative simplification is important because it allows us to solve more complex derivatives and make them easier to understand and work with.

3. What are some common algebraic rules used in derivative simplification?

Some common algebraic rules used in derivative simplification include the power rule, product rule, quotient rule, and chain rule.

4. Can all derivatives be simplified?

No, not all derivatives can be simplified. Some derivatives may require more advanced techniques or cannot be simplified at all.

5. How can I check my work when simplifying derivatives?

You can check your work by taking the derivative of the simplified expression and comparing it to the original derivative. They should be equivalent.

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