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anonymous · Answer

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anonymous · Answer

So $x \in \{1, 2, 3\}$ and $y\in \{1, 2, 3, 4, 5, 6, 7\}$.  You want to find every pair that fits the equality $2x+y=7$.

anonymous · Answer

I would start by making $y$ a function of $x$.  So we have $y(x) = -2x+7$.  I would then plug in each possible $x$.

anonymous · Answer

$$
x=1 \implies y = 5 \ 
x=2 \implies y = 3 \
x=3 \implies y = 1
$$So the answers we get is: $$F = \{(1, 5), (2,3), (3,1)\}$$

anonymous · Answer

A general heuristic I can see being useful is to make the larger set be a function of the smaller set, because you have to do less plugging stuff in.

anonymous · Answer

Okay thanks my internet connection sucks so it took me long to see this and respond to you... :)