What is the second derivative value for the function g(x)=sin (9x)?

We'll differentiate the given functin with respect to x,
using the chain rule.

g'(x) = [sin
(9x)]'

g'(x) = [cos
(9x)]*(9x)'

g'(x) = 9*cos
(9x)

Now, we'll differentiate the expression of g'(x), with
respect to x:

g"(x) = [9*cos
(9x)]'

g"(x) = 9*(-sin
(9x))*(9x)'

g"(x) = -81sin
(9x)

The value of the second derivative of
the given function is g"(x) = -81sin (9x).