Describe the concavity for the function f(x)=6+8x2x4 . Responses f(x) is concave up for the intervals (,233) and (233, ) and concave down for the interval (233, 233) . f(x) is concave up for the intervals ( , 2 3 3 ) and ( 2 3 3 , ) and concave down for the interval ( 2 3 3 , 2 3 3 ) . f(x) is concave down for the intervals (,233) and (233, ) and concave down for the interval (233, 233) . f(x) is concave down for the intervals ( , 2 3 3 ) and ( 2 3 3 , ) and concave down for the interval ( 2 3 3 , 2 3 3 ) . f(x) is concave down for the intervals (,233) and (233, ) and concave up for the interval (233, 233) . f(x) is concave down for the intervals ( , 2 3 3 ) and ( 2 3 3 , ) and concave up for the interval ( 2 3 3 , 2 3 3 ) . f(x) is concave up for the intervals (,233) and (233, ) and concave up for the interval (233, 233)