Answer: Union of two sets.
Explanation: "An element is in the union of two sets if it is in the first set, the second set, or both. The symbol we use for the union is ∪ . The word that you will often see that indicates a union is "or".
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For each equation give X a value and solve for Y, do this at least two times for each equation.
Plot those dots on a graph to draw two lines.
The solution is where the two lines cross.
You will see the lines cross at (-1,-2)
The rhombus always has perpendicular diagonals.