Identify the open intervals on which the function

y = 9 x - 18 \cos x , 0 < x < 2 \pi \text { is }

increasing or decreasing.
A) increasing on

\left( \frac { 7 \pi } { 6 } , \frac { 11 \pi } { 6 } \right) ;

decreasing on

\left( 0 , \frac { 7 \pi } { 6 } \right)

and

\left( \frac { 11 \pi } { 6 } , 2 \pi \right)

B) increasing on

\left( 0 , \frac { 11 \pi } { 6 } \right)

and

\left( \frac { 7 \pi } { 6 } , 2 \pi \right)

; decreasing on

\left( 0 , \frac { 7 \pi } { 6 } \right)

C) increasing on

\left( 0 , \frac { 7 \pi } { 6 } \right)

and

\left( \frac { 11 \pi } { 6 } , 2 \pi \right)

; decreasing on

\left( \frac { 7 \pi } { 6 } , \frac { 11 \pi } { 6 } \right)

D) increasing on

\left( 0 , \frac { 7 \pi } { 6 } \right)

and

\left( \frac { 5 \pi } { 6 } , 2 \pi \right)

; decreasing on

\left( \frac { 7 \pi } { 6 } , \frac { 5 \pi } { 6 } \right)

E) increasing on

\left( \frac { 7 \pi } { 6 } , \frac { 5 \pi } { 6 } \right)

and

\left( \frac { 5 \pi } { 6 } , 2 \pi \right)

; decreasing on

\left( \frac { 5 \pi } { 6 } , \frac { 11 \pi } { 6 } \right)

Find All Relative Extrema of the Function f(x)=x8/9−3f ( x ) = x ^ { 8 / 9 } - 3f(x)=x8/9−3

Multiple Choice