How do you use the chain rule to differentiate #sqrt(4x+9)#?

1 Answer
Aug 7, 2017

#d/(dx) [ sqrt(4x+9)] = color(blue)(2/(sqrt(4x+9))#

Explanation:

We're asked to find the derivative

#d/(dx) [sqrt(4x+9)]#

using the chain rule, which here is

#d/(dx) [sqrt(4x+9)] = d/(du)[sqrtu] (du)/(dx)#

where

  • #u = 4x+9#

  • #d/(dx)[sqrtu] = 1/(2sqrt(x))#:

#= 1/(2sqrt(4x+9)) d/(dx)[4x+9]#

The derivative of #4x + 9# is #4# (from power rule):

#= 4/(2sqrt(4x+9))#

#= color(blue)(ulbar(|stackrel(" ")(" "2/(sqrt(4x+9))" ")|)#