If #f(x) =cos3x # and #g(x) = sqrt(3x-1 #, what is #f'(g(x)) #? Calculus Basic Differentiation Rules Chain Rule 1 Answer A. S. Adikesavan Sep 27, 2016 #=-(9/2)sin(3 sqrt(3x-1))/(sqrt(3x-1)# Explanation: #f(g(x)# #=cos (3 g()x))# #=cos(3 sqrt(3x-1))# Using chain rule, #f'=(cos(3 sqrt(3x-1))'# #=-sin(3 sqrt(3x-1))(3sqrt(3x-1))'# #=-sin(3 sqrt(3x-1))((-3/2)/(sqrt(3x-1)))(3x-1)'# #=-sin(3 sqrt(3x-1))((-3/2)/(sqrt(3x-1)))(3)# #=-(9/2)sin(3 sqrt(3x-1))/(sqrt(3x-1)# Answer link Related questions What is the Chain Rule for derivatives? How do you find the derivative of #y= 6cos(x^2)# ? How do you find the derivative of #y=6 cos(x^3+3)# ? How do you find the derivative of #y=e^(x^2)# ? How do you find the derivative of #y=ln(sin(x))# ? How do you find the derivative of #y=ln(e^x+3)# ? How do you find the derivative of #y=tan(5x)# ? How do you find the derivative of #y= (4x-x^2)^10# ? How do you find the derivative of #y= (x^2+3x+5)^(1/4)# ? How do you find the derivative of #y= ((1+x)/(1-x))^3# ? See all questions in Chain Rule Impact of this question 1861 views around the world You can reuse this answer Creative Commons License