Quick question on supply and demand curve

[Ghost3k]

Ok so the problem says Let p(x)= (x+3)/(x+1) for x≥0. (a) Find p'(x). (b) If you know that p(x) is either a supply or
a demand curve, which is it, and why?

So I got part a using the quotient rule and I got -(2)/(x+1)^2.

Can anybody please help me with the second part and exactly why this is the answer?

 

[rbcc]

just guessing but if you found the derivative ( rate of change) to be negative, then that would probably be a demand curve because its downwards sloping.

 

[Ghost3k]

just guessing but if you found the derivative ( rate of change) to be negative, then that would probably be a demand curve because its downwards sloping.

thank you for answer, I think you might be right. However, just to be sure, is there anyone here that is sure that can confirm to that answer.

 

[renegade05]

Demand curves are sloped downward because of the inverse relationship between price and quantity.

If the price goes down, you buy more, and demand goes down.

So yes indeed, \(\displaystyle p(x)\) is a demand curve because \(\displaystyle p'(x)<0\) where \(\displaystyle x\geq0\)