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Why, if two wrongs don't make a right, do two negatives make a positive in mathematics?
Answer 1:

There is some math that you can do to convince yourself that multiplying 2 negative numbers gives a positive number. For example, let's say we want to evaluate -1 x (-2 +2). We know that the expression within the parentheses, -2 + 2, equals 0, so -1 x (-2 + 2) also equals 0. Using the distributive property, we know that -1 x (-2 + 2) = (-1 x -2) + (-1 x 2), which we know equals 0. The value of -1 x 2 is -2, because you simply add -1 two times. This means that (-1 x -2) must be equal to positive 2 in order for the whole expression to equal 0. This is just one of a few simple proofs you can use to show this idea.

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