Answer:
The solution is x=-2
The mistake could be in operation however here is the all operation
Step-by-step explanation:
Getting each term and sum each one

Check replacing in the original equation:

Answer:
(a) fave = 8
(b) c = 64/9
(c) c ≈ 7.111
Step-by-step explanation:
(a) The average value of the function is its integral over the interval, divided by the width of the interval.

__
(b) We want ...
f(c) = 8
3√c = 8 . . . . . use f(c)
√c = 8/3 . . . . . divide by 3
c = (8/3)² . . . . square
c = 64/9
__
(c) c ≈ 7.111
Numbers that are close in value to the actual numbers
The value of 9 is 9,000 (nine thousand)
Unlikely because certain would be 100% which is wrong