Related Rates Problem

[Ghost3k]

Where is the function Increasing and Decreasing

Ignore the Thread title please

Use the first derivative to determine where the function

is increasing and decreasing.
Use interval notion. Use U for a union (more than one interval) and leave it blank if the interval is the empty set. For

type inf .
1. Increasing (if there isn't any interval, enter none .)
2. Decreasing (if there isn't any interval, enter none .)

I was able to get the increasing part, which is (3/2,inf), but I don't know from where is it decreasing. Can anyone help me get that part.

 

[tkhunny]

You have f'(x) > 0.

Where is f'(x) = 0? Perhaps x = 3/2

Where is f'(x) < 0? Peraps everywhere else in the Domain? Did you find the Domain FIRST? That would have been a GREAT idea.

 

[Ghost3k]

You have f'(x) > 0.

Where is f'(x) = 0? Perhaps x = 3/2

Where is f'(x) < 0? Peraps everywhere else in the Domain? Did you find the Domain FIRST? That would have been a GREAT idea.

Thank you, I found the domain to be x> 3/4. So the domain it was decreasing was (3/4,3/2)

 

[wjm11]

I found the domain to be x>= 3/4. So the domain it was decreasing was (3/4,3/2)

One way to show that x = 3/4 is part of your decreasing domain, is to use "[": [3/4, 3/2)

 

[tkhunny]

...except that x = 3/4 is not in the Domain.

So, not quite right on the Domain and not quite right on the notation manages to produce an exactly correct result. {sigh}

Good work. What else have you? This was a good start.

 

[wjm11]

...except that x = 3/4 is not in the Domain.

Oops. Sorry -- not paying attention.