Math Is Fun Forum

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.)

zetafunc

Moderator

Registered: 2014-05-21

Posts: 2,440

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?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

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

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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