Question

Can anyone differentiate f(x)= (4sinx)/(2x+cos x).
Please show the way to get the answer. Thanks...

Answer 1

you can use the quotient rule

Answer 2

Quotient rule with

f'(4sin x) = 4 cos x
g'(2x + cos x) = 2 - sin x

Answer 3

Jimmyrep: yes I know but, I still can't get the right answer.

Answer 4

The answer is (8x cos x - 8sinx + 4) / (2x + cos x)^2

Answer 5

Are you okay with the denominator?

Answer 6

Did you see my derivatives:

f'g - g'f

(4cosx)(2x + cosx) - (2 - sin x)(4 sin x)

Answer 7

(2x + cos x)* 4 cos x - 4 sinx * (2 - sin x) / (2x + cos x)^2
= 8x cos x + 4 cos^2x - 8 sin x + 4 sin^2 x / (2x + cos x)^2
=[ 8 (x cos x - sin x) + 4 ] / (2x + cos x)^2

Answer 8

yes i got the step before the final answer. but I still do not understand how get their answer. help please.

Answer 9

sin^2x + cos^x = 1
so 4(cosx^x + sin^x) = 4

Answer 10

oh thanks.. i remember that use identities of trigonometry.. thank you very much all.

Answer 11

yw