Question #91477

3 Answers
Jan 7, 2018

3sin^2(x)cos(x)3sin2(x)cos(x)

Explanation:

sin^3(x)<=>(sinx)^3sin3(x)(sinx)3

Using the chain rule:

dy/dx=dy/(du)*(du)/dxdydx=dydududx

Let u=sin(x)u=sin(x)

dy/dx(sin^3(x))=dy/(du)(u)^3*(du)/dx(u)dydx(sin3(x))=dydu(u)3dudx(u)

color(white)(88888888888)=3u^2*cos(x)88888888888=3u2cos(x)

u=sin(x)u=sin(x)

color(white)(88888888888)=3sin^2(x)cos(x)88888888888=3sin2(x)cos(x)

Jan 7, 2018

3sin^2(x)cos(x)3sin2(x)cos(x)

Explanation:

Using the chain rule,

(df(u))/dx=(df)/(du)*(du)/(dx)df(u)dx=dfdududx

Let u=sin(x)u=sin(x)

(du)/(dx)=cos(x)dudx=cos(x)

f=u^3f=u3

(df)/(du)=3u^2dfdu=3u2

:.(df(u))/dx=3u^2cos(x)

Substitute u=sin(x) back, we get

:.(df(u))/dx=3sin^2(x)cos(x)

Jan 7, 2018

3sin^2xcosx

Explanation:

"differentiate using the "color(blue)"chain rule"

"given "y=f(g(x))" then"

dy/dx=f'(g(x))xxg'(x)larrcolor(blue)"chain rule"

"express "sin^3x=(sinx)^3

rArrd/dx((sinx)^3)

=3(sinx)^2xxd/dx(sinx)=3sin^2xcosx