# At what value would the derivative..

• Nov 30th 2012, 07:11 AM
salma
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?
• Nov 30th 2012, 07:18 AM
coolge
Re: At what value would the derivative..
What is the function?
• Nov 30th 2012, 07:25 AM
salma
Re: At what value would the derivative..
what function? It didnt give a function, just the graph
• Nov 30th 2012, 07:55 AM
Soroban
Re: At what value would the derivative..
Hello, salma!

Quote:

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).

Quote:

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?
• Nov 30th 2012, 07:59 AM
salma
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