Derivatives of Constant Multiples

Example:
V = ((cos(((3)/(4)))))*sin(x3/4)

The first thing to notice when finding the derivative of this function is that it is the product of a constant and another function, as shown in color below:

V = (cos(((3)/(4)))) sin(x3/4)

The Derivative Rule for Constant Multiples:

The derivative of a constant multiple is the constant times thederivative of the function.
If
  z = c ( f(x) )
then the derivative of z is
  z' = ( c f(x) )'
    = c f '(x)

So our example,

V = (cos(((3)/(4)))) sin(x3/4)
we can think of as
V = c f(x)
So the derivative is
V ' = ( c f(x) )'
  = c f '(x)  
  = (cos(((3)/(4)))) (sin(x3/4))'  
and we just need to know the derivative on the right-hand side of the equation. In this case this is
sin(x3/4) = (3/4)*cos(x3/4) x-1/4 (by the chain rule)
so the finished derivative is
V ' = (cos(((3)/(4)))) ( (3/4)*cos(x3/4) x-1/4 )
  = (3/4((cos(((3)/(4))))))*x-1/4 cos(x3/4)
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additional explanation for the derivative of constant multiples
see another derivative of constant multiples example
practice gateway test
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Comments to Gavin LaRose
glarose@umich.edu
©2001 Gavin LaRose, University of Michigan Math Dept.