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I didn't understand the question on the title, what am I supposed to do?

Delta
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  • according to the lowest what? – Newb Dec 08 '13 at 01:13
  • That's all the question says, I didn't get it – Delta Dec 08 '13 at 01:15
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    well, if we don't know what the question means, I suggest you skip this one and work on a different problem instead. – Newb Dec 08 '13 at 01:16
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    And relax a bit; you look really tense in that picture. – user99680 Dec 08 '13 at 01:17
  • I'm translating it from my language so maybe something got lost there, a more literal translation would be "express the product of the numbers in function of the lowest one"... I will relax ^^ – Delta Dec 08 '13 at 01:17
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    @Delta: Your comment translation is much better than your title one, fyi. (I would write "Express the product of the numbers as a function of the lowest one.") – Eric Stucky Dec 08 '13 at 01:19
  • a better translation would be " ... in terms of the smaller one". – bubba Dec 08 '13 at 01:52

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The question says that there are two numbers $x$ and $y$ whose sum is 318. Then it asks you to assume $x<y$ and express $xy$ using only $x$ (that is, without using $y$).

Eric Stucky
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  • I still don't get it, sorry, that means $x < 159$ how do I express 318 with only $x$ if $x < 158$ – Delta Dec 08 '13 at 01:56
  • There is still a piece of information you are not using. Try writing everything you know using equations. – Eric Stucky Dec 08 '13 at 02:08
  • You mean like $x+y=318; y=318-x;xy=x(318-x);xy=318x-x^2;$ am I on the right path or completely lost? – Delta Dec 08 '13 at 02:28
  • You tell me. Are you closer to achieving the task than before? – Eric Stucky Dec 08 '13 at 02:32
  • I don't know, I was thinking the answer is $f(x)=318x-x^2$. I'm gonna go back to studying sociology I guess – Delta Dec 08 '13 at 02:41
  • @Delta: I don't know what $f(x)$ is doing, but if it's supposed to be $xy$, then this is in fact true. But you knew this. All of the manipulations you did were correct, so certainly $318x-x^2$ is an equivalent expression for $xy$. And your final answer did not use $y$, so you have done exactly what the question has asked! – Eric Stucky Dec 08 '13 at 02:44
  • I guess it makes sense then, except I didn't understand where the info about $x < y$ would influence the equation – Delta Dec 08 '13 at 02:46
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    @Delta: Okay! Well, it's good that you don't understand why that matters, because it doesn't; $xy=318y-y^2$ as well. (But that's the sort of information I would have liked to see in your second comment!) – Eric Stucky Dec 08 '13 at 02:57