9000070407

SubArea: 
Function Behavior
Level: 
A
Project ID: 
9000070407
Source Problem: 
9000070408
Accepted: 
1
Clonable: 
1
Easy: 
0
Given the function \(f(x) = -x^{3} + 3x^{2} + 9x - 1\), find the intervals where \(f\) is a decreasing function.
\(\left (3,\infty \right )\)
\(\left (-\infty ,1\right )\)
\(\left (-1,3\right )\)
\(\left (1,\infty \right )\)