Here we study the derivative of a function, as a function, in its own right.

The derivative of a function, as a function

We know that to find the derivative of a function at a point we write However, if we replace the given number with a variable , we now have This tells us the instantaneous rate of change at any given point .

Suppose you are given a polynomial and you are asked to compute . What is the most efficient way to answer the question?
Suppose you are given a polynomial and you are asked to compute , , and . What is the most efficient way to answer the question?

Given a function from the real numbers to the real numbers, the derivative is also a function from the real numbers to the real numbers. Understanding the relationship between the functions and helps us understand any situation (real or imagined) involving changing values.

Let . What is ?
Here we see the graph of .
PIC
Describe when is positive. Describe when is negative. When is positive, is . When is negative, is
Which of the following graphs could be ?