<p>if x+y/x and y is a positive integer what is the value of x?
a) -y
b) 0
c)y</p>
<p>Well I’m not a math teacher but the answer would seem to by “y.”</p>
<p>Let’s say y=1</p>
<p>Plug it in.</p>
<p>x+1/x</p>
<p>The x’s cancel out, leaving me with “1,” which is the value I substituted for y.</p>
<p>Now I’m curious…</p>
<p>Let’s try it with y equaling 649.</p>
<p>x+649 divided by x…</p>
<p>The x’s cancel out, leaving me with 649, which equals “y.”</p>
<p>I hope I’m right (and I hope that helps).</p>
<p>thanks for trying 
but it is actually wrong…the answer is a…which is -y</p>
<p>anyonee :)</p>
<p>The mistake you’re making is that you’re “cancelling out” x, jkjeremy, in that fraction. Try with (2+3)/2=5/2 and (2+3)/2===cancelling===> 3.</p>
<p>Smartyfox, do you have more information for the problem? I know that y is a positive integer, and there is a value defined as (x+y)/x, but are there any restrictions on what the answer needs to be? For example, the answer you give (a), or -y, suggests that the expression (x+y)/x=(-y+y)/(-y)=0/(-y)=0.</p>
<p>However, without restrictions, the answer could just as easily be (c), or y, because (2y)/y=2, for all positive integer values of y (and non-integer values of y as well).</p>
<p>The only answer it couldn’t be would be (b), or 0, because plugging in, we’d get (0+y)/0, and dividing by zero means the world ends.</p>
<p>noo… i wrote the question just as it is written exactly.
in the answers and explantions it says that
x+y/y=0
x=-y
BUT I DONT UNDERSTAND WHY DID HE DO IT EQUAL TO ZERO !!!</p>
<p>I feel that you wrote the question incorrectly. Two interpretations of the question came to mind:</p>
<p>Case 1: Grammatical error (change “is a positive integer” to “are positive integers”). If this is so, then (x+y)/x = 1 + y/x. However any value of x such that y/x is a nonnegative integer works.</p>
<p>Case 2: “If (x+y)/x = 0 and y is a positive integer…” Then clearly, x = -y.</p>
<p>Basically, you should really check whether you’ve written the problem correctly. As a math major and someone who’s written math contest questions, there appears to be a flaw in the question.</p>
<p>LOL. I’m sorry if i misled the person who had the question. I’m an English teacher, so I guess I should stay out of post-4th grade math. Luckily (and hopefully) I can still help the kids in my family.</p>
<p>However, I’m gonna check this thread again because now I’m curious how it’s gonna turn out.</p>
<p>I second MITer. This is a flawed question as written. Either it has not been correctly presented to us, or it is incorrect in OP’s study guide.</p>
<p>I guess if they’re setting (x+y)/x = 0 then my second interpretation seems likely…however in that case it just doesn’t look like a well written question.</p>