Determine Whether the Function Is a Probability Density Function Over $$f ( x ) = 9 ^ { x } \text { over } \left[ 0 , \frac { \ln ( 1 + \ln 9 ) } { \ln 9 } \right]$$

True/False

Determine whether the function is a probability density function over the given interval.
- $$f ( x ) = 9 ^ { x } \text { over } \left[ 0 , \frac { \ln ( 1 + \ln 9 ) } { \ln 9 } \right]$$