# Math modeling question ???

• Mar 25th 2008, 03:12 PM
kbgemini16
Math modeling question ???
How can I write an expression for the sum of two(unknown) numbers in terms of just x ?

Can I write:

x=1/y

or ....

x=1/X ?
• Mar 25th 2008, 09:22 PM
CaptainBlack
Quote:

Originally Posted by kbgemini16
How can I write an expression for the sum of two(unknown) numbers in terms of just x ?

Can I write:

x=1/y

or ....

x=1/X ?

More detail please, this question makes no sense (to me at least) as it stands.

RonL
• Mar 26th 2008, 04:47 AM
kbgemini16
No Clue...
The directions are to create an expression that represents two unknown numbers for which I will use "x" & "y" to represent them. How can I write an expression for their sum in terms of just X

So since it's asking for an expression for the sum of the two unknown numbers I know the expressions that I need to create will have a "+" but I can't show the expression in terms of just "x"

I was thinking that:
f(x)=x+y

or...

f(x)=1/y

or...

f(x)=1/x

I don'rt know, I'm lost because I don't understand the part of the question that asks for the sum in terms of just "x" ....

(Worried)

Quote:

Originally Posted by CaptainBlack
More detail please, this question makes no sense (to me at least) as it stands.

RonL

• Mar 26th 2008, 06:05 AM
CaptainBlack
Quote:

Originally Posted by kbgemini16
The directions are to create an expression that represents two unknown numbers for which I will use "x" & "y" to represent them. How can I write an expression for their sum in terms of just X

There is something wrong here are X and x the same thing?
• Mar 26th 2008, 06:12 AM
kbgemini16
Yes "X" & "x" are the samething my error ...(Doh)
• Mar 26th 2008, 07:33 AM
CaptainBlack
Quote:

Originally Posted by kbgemini16
Yes "X" & "x" are the samething my error ...(Doh)

Then I think what you ask is impossible. It is possible to create a number that
encodes two numbers (think of interleaving the digits of a decimal expansion)

RonL
• Mar 26th 2008, 10:33 AM
iknowone
Is it known how x and y are related? In other words can you express one of the unknowns in terms of the other (for example maybe y=x^2)? Then expressing the sum of the two unknowns in terms of just one unknown is a triviality.