Find the intervals on which the function is increasing and the intervals on which the function is decreasing.
-$$f ( x ) = - \frac { 1 } { 3 } x ^ { 2 } + 7 x - 8$$
A) Increasing on $\left( - \infty , \frac { 21 } { 11 } \right)$; decreasing on $\left( \frac { 21 } { 11 } , \infty \right)$
B) Increasing on $\left( - \infty , \frac { 21 } { 2 } \right)$; decreasing on $\left( \frac { 21 } { 2 } , \infty \right)$
C) Increasing on $\left( - \infty , \frac { 21 } { 13 } \right) ;$ decreasing on $\left( \frac { 21 } { 13 } , \infty \right)$
D) Increasing on $\left( - \infty , \frac { 21 } { 4 } \right) ;$ decreasing on $\left( \frac { 21 } { 4 } , \infty \right)$

Question

Quizplus · Accepted Answer

The Answer of Find the intervals on which the function is increasing and the intervals on which the function is decreasing.
-$$f ( x ) = - \frac { 1 } { 3 } x ^ { 2 } + 7 x - 8$$
A) Increasing on $\left( - \infty , \frac { 21 } { 11 } \right)$; decreasing on $\left( \frac { 21 } { 11 } , \infty \right)$
B) Increasing on $\left( - \infty , \frac { 21 } { 2 } \right)$; decreasing on $\left( \frac { 21 } { 2 } , \infty \right)$
C) Increasing on $\left( - \infty , \frac { 21 } { 13 } \right) ;$ decreasing on $\left( \frac { 21 } { 13 } , \infty \right)$
D) Increasing on $\left( - \infty , \frac { 21 } { 4 } \right) ;$ decreasing on $\left( \frac { 21 } { 4 } , \infty \right)$

Find the Intervals on Which the Function Is Increasing and the Intervals