Derivative not correct for online hw submission, but is correct

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Homework Help Overview

The problem involves finding the derivative of the function (x^2 + 2x + 5)^2, with a focus on applying the chain rule correctly. Participants are discussing the application of differentiation rules in this context.

Discussion Character

  • Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants are examining the application of the chain rule and whether it was applied correctly in the original attempt. Some suggest an alternative approach of multiplying out the expression before differentiating.

Discussion Status

The discussion is ongoing, with some participants questioning the correctness of the derivative provided by the original poster. There is a mix of interpretations regarding the application of the chain rule, and some guidance has been offered on how to approach the differentiation.

Contextual Notes

There is mention of a math instructor's input, which adds to the complexity of the discussion regarding the correctness of the derivative. The original poster expresses confusion stemming from feedback received in a university math lab.

Torshi
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Homework Statement


Find the d/dx
(x^2+2x+5)^2


Homework Equations




Chain rule

The Attempt at a Solution



My answer:

2(x^2+2x+5)*(2x+2)*2
 
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Why did you apply the chain rule again to (2x+2)? You only need to do it once.

It should be:

##2(x^2 + 2x + 5)(2x + 2)##

Think of it this way: ##f(x) = x^2## and ##g(x) = x^2 + 2x + 5##.

Then, ##D(f \circ g)(x) = Df(g(x))D(g(x))##
 
Last edited:
You could also just multiply it out and use the power rule.
 
Torshi, your title is misleading. The derivative you show is not correct for online submission, AND it is not correct, as Karnage1993 points out.
 
Mark44 said:
Torshi, your title is misleading. The derivative you show is not correct for online submission, AND it is not correct, as Karnage1993 points out.

I didn't mean it to be misleading. My fault. The reason why I said that was because I was at my university math lab and even one of the math instructors said it was correct, but made a tad mistake until I mentioned it. I figured out the answer though.
 

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