Answer
The function $f$ has a relative maxima $f\left( b \right)$ at point $b$ and a relative minima $f\left( a \right)$ at point $a$.
Work Step by Step
The function $f$ is increasing on an interval $\left( a,b \right)$ ,
This means that the relative maxima of function $f$ is $f\left( b \right)$ at point $b$ and the relative minima $f\left( a \right)$ at point $a$.
