Question

How do you differentiate `y = 3x cos (x/3) - sin (x/3)`?

Answer 1

the answer
`y'=[8cos(x/3)]/3-xsin(x/3)`

Explanation:

show below

`y = 3x cos (x/3) - sin (x/3)`

`y'=3[x*-1/3sin(x/3)+cos(x/3)*1]-1/3*cos(x/3)`

`y'=-x*sin(x/3)+3cos(x/3)-1/3*cos(x/3)`

`y'=[8cos(x/3)]/3-xsin(x/3)`