How do you differentiate f(x) =cos(3x -2) f(x)=cos(3x2)?

1 Answer
Mar 7, 2016

(df)/dx = -3sin(3x-2)dfdx=3sin(3x2)

Explanation:

Use substitution.

If you have a function like this, let,say, t =3x -2t=3x2
Then f(t) = costf(t)=cost and (df)/dt = -sintdfdt=sint
(dt)/dx = 3dtdx=3
(df)/dx = (df)/dt*(dt)/dx = -sint*3dfdx=dfdtdtdx=sint3

(df)/dx = -3sin(3x-2)dfdx=3sin(3x2)