Question

Find increasing and decreasing intervals of f(x)

f(x)=-5x^2-40x-28

Answer 1

need help

Answer 2

yes!

Answer 3

Are you supposed to use calculus or do it in another way?

Answer 4

calculus, which is my problem haha

Answer 5

ok

Answer 6

Ok, because this problem can be done in other ways to.
Now, you need to see if the function is increasing or decreasing, and what tells you that is the derivative, wich is the rate of change of the function as you change the x variable.
If this rate of change is positive, then the function is increasing, if it is negative, the function is decreasing.
Did you manage to find the derivative?

Answer 7

I think it might be increasing on (-infinity,-4) and decreasing on (-4,infinity)

Answer 8

This is basically a foreign language for me

Answer 9

The derivative is -10x-40

Answer 10

yes got that to

Answer 11

The derivative is correct, but when you made it equal to zero you got the x wrong, so the intervals are wrong but it was probably a small mistake.

Answer 12

hmmm, well -10x-40=0 x=-4?

Answer 13

yea

Answer 14

hahaha, the small mistake was mine

Answer 15

So your answer was correct in the first place

Answer 16

those are the only intervals? and I have them correct? the increasing and decreasing

Answer 17

yea u was wright

Answer 18

yep