What is the Derivative of -sinx?

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Discussion Overview

The discussion revolves around the derivative of the function -sin(x). Participants explore the rules of differentiation, particularly focusing on the application of constants in derivative calculations.

Discussion Character

  • Technical explanation

Main Points Raised

  • One participant states that the derivative of cos(x) is -sin(x) and questions whether the derivative of -sin(x) is cos(x) or 1/cos(x).
  • Another participant clarifies that the derivative of -sin(x) is -cos(x), explaining that the negative sign can be treated as a constant factor.
  • A later reply emphasizes the rule that the derivative of a constant is zero and illustrates how to apply the constant multiple rule in differentiation.
  • One participant provides a link to a resource for further reference on the topic of derivatives.

Areas of Agreement / Disagreement

Participants generally agree on the application of the constant multiple rule in differentiation, but there is some initial confusion regarding the derivative of -sin(x) that remains unresolved.

Contextual Notes

There is an assumption that participants are familiar with basic differentiation rules, and the discussion does not resolve the initial confusion regarding the derivative of -sin(x) as presented in the first post.

Sakha
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I know the derivative of cos(x) = -sinx
is the derivative of -sinx= cosx
or maybe derivative of -sinx = 1/cosx
which is it
 
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Derivative of sin(x) is cos(x).
Derivative of (-1)*(sin(x))= (-1) (cos(x))
The - is just a constant you can take out front.
 
Thanks i got it
 
Last edited:
With respect to some variable, the derivative of a constant is zero. However by recognizing (-1) as a constant multiple while taking the derivative of a function of a variable with respect to that variable, you can write:
d/dx((-1)(f(x))= (-1) d/dx(f(x)) = (-1) (f'(x)

Edit: http://en.wikipedia.org/wiki/Table_of_derivatives
See: Linearity
 

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