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#1 2018-05-27 19:33:36

Loki
Guest

algebra

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.)

#2 2018-05-27 22:57:19

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,225
Website

Re: algebra

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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#3 2018-05-28 00:37:34

bob bundy
Registered: 2010-06-20
Posts: 8,496

Re: algebra

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

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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