Find the average interval of function 3x^3-12x^2 on the interval [-5,4]?

Question

My answer is 114.75 but when i put it on submission , it tell me that its wrong not sure why kindly help and tell me right answer

Answer 1

I guess maybe you mean the average value of the function in that domain.
integral = (3/4)x^4-4x^3
at -5 = (3/4)625-4(-125) = 968.75
at 4 = (3)64-4(64) = -64
so I get
968.75 + 64 = 1032.75
divide by length of domain, 9
I agree with you, 114.75

Answer 2

I think you subtracted wrong. Try

(f(4)-f(-5))/9 = -114.75

as a quick look at the graph would indicate:

http://www.wolframalpha.com/input/?i=3x%5E3-12x%5E2

Answer 3

I have put both of these answer's but still wrong don't know what to do

Answer 4

well, I get -114.755

so maybe the key wants -114.76 or -114.8 or -115