Question

I didn't get it. Can someone explaint to me?

Answer 1

could you please explain to me what your problem is.

Answer 2

I did not undestand the explanation in the picture.

Answer 3

I was using my son's account. I did not undestand the explanation in the picture.

Answer 4

yes the picture is a bit odd im sorry

Answer 5

ok

Answer 6

is this precalc or calc

Answer 7

Here is a video that goes over this idea
http://www.khanacademy.org/math/calculus/differential-calculus/derivative_intro/v/calculus--derivatives-1--new-hd-version

The video will explain it better than what I can type in here... but
the idea is you have y= f(x) meaning y is a function of x
for each x, you can find a y to get an (x,y) pair.
say you find two (x,y) pairs. you can find the slope between those two pair by calculating the change in y divided by the change in x

for example, in choice A, they let the first x point be a-4h (a is some number and h is another number.)
they let the 2nd x point be x= a+2h

the slope is the change in y, which is f(a+2h) - f(a-4h)
divided by the change in x: a+2h - (a-4h)= a+2h -a +4h = 6h
the slope is
\[ \frac{ f(a+2h) - f(a-4h)}{6h} \]
the expression in choice A is dividing by -2h which is not correct. so choice A is out.

If this explanation does not make sense, try the video.

Answer 8

It's Calculus, from mooculus, https://class.coursera.org/calc1-001.

Answer 9

Thank you phi. Let me see the video.

Answer 10

Sal is awesome, he is an amazing guy.