Question

Use the equation given below to find f '' (π/3).
f (x) = sec(x)

Answer 1

first find f'(x) this is sec(x)tan(x). then find f''(x). you have to use the product rule to find the second derivative: take the derivative of sec(x) * tan(x) + the derivative of tan(x)*sec(x). once you have this you can just plug in pi/3 and solve.

Answer 2

i got 48 but it showed my answer as wrong

Answer 3

what did you get from the product rule?

Answer 4

f'g+fg'

Answer 5

I got sec(x)tan(x)tan(x) + sec(x)sec^2(x).

Answer 6

... do the product rule and tell me what you get.

Answer 7

The is because Sec'(x) is sec(x)tan(x) and tan'(x) is sec^2(x)

Answer 8

how do i find sec^2(pi/3)

Answer 9

it is the same as sec(pi/3)sec(pi/3) so you should get 2*2

Answer 10

i got 14

Answer 11

is that correct?

Answer 12

hmmm i got 11. so sec(pi/3) is 2 and tan(pi/3) is (SQRT3)/2. So I got 2*(SQRT3)/2*(SQRT3)/2 + 2*2*2 this simplifies to 3 +8 which is 11

Answer 13

WAIT thats wrong....

Answer 14

it should be 3/2 + 8

Answer 15

isnt tan pi/3 just SQRT 3?

Answer 16

so you would 2*sqrt 3*sqrt3+2*2*2

Answer 17

oops yes you're right, sorry my trig isnt so great

Answer 18

lol thats ok

Answer 19

so does make it 14?