system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: In math, when multiplying, why do two negatives make a positive?
gpt
Think about it like this: If you film someone running forwards (positive) and then play the film forward (positive) he is still running forward (positive). If you play the film backward (negative) he appears to be running backwards (negative) so the result of multiplying a positive and a negative is negative. Same goes for if you film a guy running backwards (negative) and play it normally (positive) he appears to be still running backwards (negative). Now, if you film a guy running backwards (negative) and play it backwards (negative) he appears to be running forward (positive). Even if you speed up the rewind (-3x or -4x) these results hold true. Backward x backward = forward. Negative times negative = positive.