How do you differentiate f(x)=sin23x(x1)2cos2x using the chain rule?

1 Answer
Mar 30, 2017

dfdx=32xsin12x(x1)2(x+1)(x1)2cos2xsin23x(x1)2sin2x

Explanation:

Let us first differentiate g(x)=sin23x(x1)2

let us write this as chain, where g(x)=sin2(h(x)), h(x)=p(x),

p(x)=3x(x1)2 and using chain rule

dg(x)dx=dgdh×dhdp×dpdx

= 2sin(h(x))cos(h(x))×12p(x)×3(x1)26x(x1)(x1)4

= sin(2h(x))×12p(x)×3x26x+36x2+6x(x1)4

= sin12x(x1)2×123x(x1)2×3x2+3(x1)4

= 3sin12x(x1)2×123x×x21(x1)3

= 32xsin12x(x1)2(x+1)(x1)2

and hence

dfdx=32xsin12x(x1)2(x+1)(x1)2cos2xsin23x(x1)2sin2x