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**Loki****Guest**

Find all integers x for which there exists an integer y such that

1/x + 1/y =1/7.

(In other words, find all ordered pairs of integers (x,y) that satisfy this equation, then enter just the x's from these pairs.)

Hello,

I noticed that you've posted several times here as a guest. Why not register an account with us?

What have you tried? What sorts of restrictions do you think you can place on x and y?

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,400

hi Loki,

Re-arrange the equation to make y the subject. As x is an integer so is X+7 so replace x by X+7 and simplify that equation for y.

It should be fairly easy to work out which values of X (I can only see three and three more negative that will work) so you can then convert back to get values of x.

Bob

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