21 I think sorry if I am wrong
What are the choices, or do you have to give the answer?
Answer:
it aproximatley 7.937 rounded to the nearest tenth its 7.9
Step-by-step explanation:
We are given our function as

For finding concavity , firstly we will find second derivative



now, we can find derivative again




now, we can know second derivative is undefined when denominator =0
so, we set denominator =0
and then we can solve for x


now, we can draw a number line and locate x=-4
and then we can find sign of second derivative on each intervals
so,
Concave downward interval:
