2015 UMO Problems/Problem 5

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Problem

A $3 \times 3$ grid is filled with integers (positive or negative) such that the product of the integers in any row or column is equal to $20$. For example, one possible grid is:

$\begin{bmatrix}    1 & -5& -4 \\     10  & -2 &-1 \\    2& 2& 5 \end{bmatrix}$

In how many ways can this be done?

Solution

See Also

2015 UMO (ProblemsAnswer KeyResources)
Preceded by
Problem 4
Followed by
Problem 6
1 2 3 4 5 6
All UMO Problems and Solutions
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