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Linear Approximation

  • Thread starter Fiorella
  • Start date
  • #1
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Homework Statement



Here is a picture of the problem: http://i3.photobucket.com/albums/y62/Phio/34.jpg" [Broken]

Homework Equations



y - f(c) = f '(c) (x - c)

The Attempt at a Solution



1/(5+x)^1/2 = (5 + x) ^ -1/2 = (1/5)^(1/2) * (1 + x/5)^(-1/2)

I have this. But I don't know if i'm on the right track...
 
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Answers and Replies

  • #2
HallsofIvy
Science Advisor
Homework Helper
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I don't know what you are doing! You have rewritten the formula in a couple of different ways but you seem to have made no attempt to find either f'(c) or f(c), which you need to use "y- f(c)= f'(c)(x- c)".
 
  • #3
tiny-tim
Science Advisor
Homework Helper
25,832
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Hi Fiorella! :smile:

(try using the X2 tag just above the Reply box :wink:)
1/(5+x)^1/2 = (5 + x) ^ -1/2 = (1/5)^(1/2) * (1 + x/5)^(-1/2)

I have this. But I don't know if i'm on the right track...
(I've no idea why you think "y - f(c) = f '(c) (x - c)" is relevant :confused: … but anyway:)

The answers given are clearly wrong :frown:

at x = 0, f(x) = 1/√5, which does not match.

But your method is correct …

just carry on regardless! :smile:
 

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