What is the derivative of f(x) = e^-xcos(x^2)+e^xsin(x)f(x)=excos(x2)+exsin(x)?

1 Answer
Jul 9, 2016

=-e^(-x)cos(x^2) - 2xe^(-x)sin(x^2) + e^xsin(x) + e^xcos(x)=excos(x2)2xexsin(x2)+exsin(x)+excos(x)

Explanation:

Product rule is our friend here.

d/(dx) (e^(-x)cos(x^2)) + d/(dx)(e^xsin(x))ddx(excos(x2))+ddx(exsin(x))

=d/(dx)(e^(-x))cos(x^2) + e^(-x)d/(dx)(cos(x^2)) + d/(dx)(e^x)sin(x) + e^xd/(dx)(sin(x))=ddx(ex)cos(x2)+exddx(cos(x2))+ddx(ex)sin(x)+exddx(sin(x))

=-e^(-x)cos(x^2) - 2xe^(-x)sin(x^2) + e^xsin(x) + e^xcos(x)=excos(x2)2xexsin(x2)+exsin(x)+excos(x)

NB: for d/(dx)(cos(x^2))ddx(cos(x2)) I have used the chain rule because x^2x2 is also a function of x