Discussion:  All Topics in PreCalculus for Properties of Rational Functions 
Topic:  Need some quick help 
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Subject:  RE: Need some quick help 
Author:  DUB 
Date:  Aug 1 2004 
Can you help on these two as well?
 Suppose you have a lemonade stand, and when you charge $1 per cup of lemonade
you sell 60 cups. But when you raise your price to $2 you only sell 30 cups.
Write an equation for the number of cups you sell as a function of the price
you charge. Denote "C" for number of cups, and "P" for the price you charge.
Assume the function is linear.
 Take a look at the table below and write out an equation for f(x).
x 2 1 0 1 2
f(x) 5 2 1 4 7
 Thanks again,
On Jul 31 2004, ycc wrote:
> To answer your question, you need to make clear what is the
> definition of a function. To say a function, we have to tell clearly
> what are the domain and codomain. (i.e. the region for the starting
> value and the region for the ending value.)
A function means that
> for any value x in the domain, there is one and only one value y in
> the codomain such that f(x)=y.
(Please check your boook if you are
> still unsure the definition.)
Please see my responses inserted.
On
> Jul 31 2004, Tryin wrote:
> Hey Folks,
I have just went out and
> purchased some software to
> help educate myself with Algabra.
> However, I do need some quick
> help on the following problems. If
> anyone can help me, It would be
> deeply appreciated. I'm trying
> to help my kid but I am not doing a
> good job at all. Thanks
> I assume the domain and codomain are the set of real numbers.
> 1. Which of the following are
> functions? Explain your reasoning
> for a, b, and c.
a. f(x) = 2
> if x>1
f(x) = 1
> otherwise
YES. Every x has one and only one corresponding real
> value.
b. f(x) = 5 if x>0
> f(x) = 5 if x<0
f(x) = 5
> or 5 if x = 0
NO. There are two values for f(0), which is not
> allowed. (Every x should have only one corresponding value f(x).)
> c. f(x) =
> 10/x
NO. f(0)=10/0 is not a real number. (Every x
> should have a corresponding value f(x).)
 
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