Rational functions

9000007510

Level: 
B
The graph of the function \[ f(x) = \frac{-x + 1} {1 + 3x} \] is a hyperbola. Find the center of this hyperbola.
\(S = \left [-\frac{1} {3};-\frac{1} {3}\right ]\)
\(S = \left [\frac{1} {3}; \frac{1} {3}\right ]\)
\(S = \left [1;-\frac{1} {3}\right ]\)
\(S = \left [-1;-\frac{1} {3}\right ]\)
\(S = \left [-\frac{1} {3}; \frac{1} {3}\right ]\)