Derivative not correct for online hw submission, but is correct

  • Thread starter Torshi
  • Start date
  • #1
118
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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
 

Answers and Replies

  • #2
133
1
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:
  • #3
559
8
You could also just multiply it out and use the power rule.
 
  • #4
34,158
5,777
Torshi, your title is misleading. The derivative you show is not correct for online submission, AND it is not correct, as Karnage1993 points out.
 
  • #5
118
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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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