Derivatives of Constant Multiples
Example:
C(y) = 3*(ln(y))1/4
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:
The Derivative Rule for Constant Multiples:
The derivative of a constant multiple is the constant times thederivative of the function.
If
then the derivative of
z is
| |
z' |
= |
( c |
f(x) )' |
| |
|
= |
c |
f '(x) |
So our example,
we can think of as
So the derivative is
| C '(y) |
= ( |
c |
f(y) |
)' |
| |
= |
c |
f '(y) |
|
| |
= |
3 |
((ln(y))1/4)' |
|
and we just need to know the derivative on the right-hand
side of the equation. In this case this is
| (ln(y))1/4 |
= |
(1/4)*(ln(y))-3/4 y-1 |
(by the chain rule) |
so the finished derivative is
| C '(y) |
= |
3 |
( (1/4)*(ln(y))-3/4 y-1 ) |
| |
= |
(3/4)*y-1 (ln(y))-3/4 |
![[]](/images/boxby.gif)
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.