# Thread: At what value would the derivative..

1. ## At what value would the derivative..

1) At what value(s) of x, if any, would the value of the derivative be equal to zero?
A) When x=c and x=e only.
B) When x=b only.
C) When x=a, x=b, x=c, and x=d.
D) When x=a, x=b, and x=d.
Here, I put C.

2) At what value(s) of x would the derivative not exist?
A) When x=c and x=e only.
B) When x=c only.
C) When x=a, x=b, x=d, and x=e only.
D) When x=a, x=b, and x=d only.
Here, I put A.

Am I right on these?

2. ## Re: At what value would the derivative..

What is the function?

3. ## Re: At what value would the derivative..

what function? It didnt give a function, just the graph

4. ## Re: At what value would the derivative..

Hello, salma!

1) At what value(s) of $\displaystyle x$, if any, would the value of the derivative be equal to zero?

A) When $\displaystyle x=C$ and $\displaystyle x=E$ only.
B) When $\displaystyle x=B$ only.
C) When $\displaystyle x=A,\:x=B,\:x=C,\:x=D$
D) When $\displaystyle x=A,\:x=B,\:x=D$
. . Here, I put C. . . . . no

There is a vertical tangent at C.
The derivative is DNE (does not exist).

2) At what value(s) of $\displaystyle x$ would the derivative not exist?

A) When $\displaystyle x=C$ and $\displaystyle x=E$ only.
B) When $\displaystyle x=C$ only.
C) When $\displaystyle x=A,\:x=B,\:x=D,\:x=E$ only.
D) When $\displaystyle x=A,\:x=B,\:x=D$only.
. . Here, I put A. . . . . no

You are half-right.
The derivative is DNE at $\displaystyle x = C.$

But the derivative does exist at $\displaystyle x = E.$

The point itself does not exist.
But you can sketch the tangent line there, can't you?

5. ## Re: At what value would the derivative..

umm ok I think i got it now, so for the 1st one, would it be D then?
and then the 2nd one would be B