Derivatives in my calculus class

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Discussion Overview

The discussion revolves around methods for verifying the correctness of derivative calculations in a calculus class. It includes various approaches and techniques that students can use to check their work, as well as considerations regarding the participant's level of understanding.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests performing the problem twice to check for consistency in answers.
  • Another proposes graphing the function to observe whether it increases only where the derivative is positive.
  • A different participant recommends using the derivative to compute tangent lines and verifying their tangency to the graph.
  • One suggestion involves evaluating the derivative at a point and checking the limit definition by calculating a small difference quotient.
  • Another participant mentions integrating the derivative to see if it yields the original function.
  • There is a concern raised about the appropriateness of using indefinite integration at the participant's current level of study.
  • A later reply challenges the assumption that the participant has learned the Fundamental Theorem of Calculus, implying a potential gap in knowledge.

Areas of Agreement / Disagreement

Participants express differing views on the appropriateness of certain methods for verifying derivatives, particularly regarding the use of integration. There is no consensus on the best approach, and some participants question the foundational knowledge of the original poster.

Contextual Notes

There are assumptions regarding the participant's familiarity with concepts such as the Fundamental Theorem of Calculus and indefinite integration, which may affect the applicability of some suggested methods.

Who May Find This Useful

Students currently learning calculus, particularly those seeking strategies for verifying their derivative calculations.

Haroldoo
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I am on my second day of derivatives in my calculus class (I am taking it over the summer) and I was wondering if there is a check that you can preform to see if your answer is correct?
I do some questions and I think I got it right but I am just never sure if I have made an arithmatic error or somthing, somewhere.
 
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You could do the problem twice, see if you get the same answer. Similarly, you could try to do the same problem in multiple ways.

You could graph the function and see if it is increasing only where the derivative is positive. You could use the derivative to compute some tangent lines, and see if the tangent line really is tangent to the graph.

The derivative is a limit -- you could try plugging in a value that is near the limiting point, to see if you get something nearly equal to the derivative.
 
Sure, here's a trick. Suppose you evaluate the derivative of f(x) at x0 to be L. Try evaluating [f(x0+0.0001]-f(x0)]/0.0001 with your calculator. You should get approximately L.
 
Try integrating the answer and seing if you come up with the original function
 
Gza said:
Try integrating the answer and seeing if you come up with the original function

He's on his third day on differentiation, I don't think indefinite integration is quite within his reach yet.
 
Gib Z said:
He's on his third day on differentiation, I don't think indefinite integration is quite within his reach yet.

sure it is considering the indefinite integral is just the antiderivative:-p
 
>.< Well I'm not sure he's learned the Fundamental Theorem of Calculus either ! :P
 

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