![]() |
If the line is horizontal then the outputs don't change so the function is constant.
When you zoom in on most functions they look like straight lines. (The functions for which this works are called differentiable functions --- there ARE functions which are not differentiable, but we'll get to those later.) In any case you can tell whether a function is increasing or decreasing by zooming in and determining whether the straight line is increasing or decreasing.
This means that the study of (differentiable) functions is largely a matter of understanding what happens with straight line (or linear) functions.
If you are having trouble with a problem
it is good to seek help from a human!
This could be a fellow student, the TA or the professor. It is also helpful to look
at the relevant chapter of the textbook. You can use the index to look up key words
if you're not sure where to look.
Don't waste too much time guessing at answers!
Read the book, your notes. Talk to someone! Print out a hard copy of the problem set and take it down to the Pit to work on!
You can use the Feedback button at the bottom of each problem page to send e-mail to the TA and to the professor.