# Thread: Math modeling question ???

1. ## 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 ?

2. 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

3. ## 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" ....

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

RonL

4. 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?

5. Yes "X" & "x" are the samething my error ...

6. Originally Posted by kbgemini16
Yes "X" & "x" are the samething my error ...
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

7. 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.