How do you differentiate log_3(9x^2sin(9x^2) ) ?

1 Answer
Mar 31, 2017

see below

Explanation:

Use the following Properties of Logarithm to expand the problem before taking derivatives.

  1. color(red)(log_b(xy)=log_bx+log_by
  2. color(red)(log_b(x/y)=log_bx-log_by
  3. color(red)(log_b x^n =n log_bx

Then use the formula color(red)(d/dx(log_bx)=1/(xln b) to find the derivative

y=log_3(9x^2sin(9x^2))

y=log_3 9 + log_3x^2+log_3 sin(9x^2)

y=log_3 9 + 2 log_3x+log_3 sin(9x^2)

color(blue)(y'=0+2/(xln3)+1/(sin(9x^2)ln3) * cos (9x^2)*18x

color(blue)(y'=2/(xln3)+(cos (9x^2)*18x)/(sin(9x^2)ln3)

color(blue)(y'=2/(xln3)+((18x) cot(9x^2))/ln3

color(blue)(y'=((18x^2) cot(9x^2))/(xln3)