Question

Find the value of the derivative (if it exists) at each indicated extremum. (If an answer does not exist, enter DNE.)
f (x) = cos(πx/2)
http://www.webassign.net/larson/3_01-04.gif

Answer 1

what I have so far for the derivative is f'(x)= -sin(pix/2)(pi)

Answer 2

or (pi)-sin(pix/2)

Answer 3

which is wrong

Answer 4

The thing inside sine is pix/2 instead of pix

Answer 5

You have to divide by 2

Answer 6

so (pi/2)-sin(pix/2). or am I not understanding this properly.

Answer 7

This looks like (pi/2) minus sin(pix/2)

Answer 8

Is this what you mean

Answer 9

yes

Answer 10

Then it's wrong

Answer 11

[f(g(x))]' = f'(g(x)) * g'(x)

Answer 12

Ok so then derivative of cos is -sin. we leave the inner fucntion alone, thus (pix/c2. then it is multiplied by the derivative of the inner function (pi/2),by the outer function cos. so -sin(pix/2)cos(pi/2). correct?

Answer 13

Nope

Answer 14

pi/2 instead of cos(pi/2)

Answer 15

just multiply by the derivative of the inner function (pi/2)

Answer 16

gotcha. So there was no need for me to bring the (pi/2) in front of the function. Wow I must rest then. lol

Answer 17

If you were to bring it in front of the function

Answer 18

Place the negative sign in the very front

Answer 19

-(pi/2)sin(pix/2)

Answer 20

That is very true. It keeps the function the same. what i was doing was changing the function itself by not including the factor in the function.

Answer 21

Back to the question shall we

Answer 22

ok. I just needed assistance in finding the derivative to this equation.

Answer 23

thanks kc_kennylau

Answer 24

no problem