Archive for the ‘maths’ Category

When a minus times a minus equals a plus

We all know from school that multiplying two negative numbers together gives a positive number, but can you think of a common-sense example of this rule in action that would convince someone who asked why? I got asked why recently and I couldn’t. Neither could anyone I asked. Plenty of examples involving mirrors and vectors [...]

Posted on September 19, 2009 at 11:22 am by Paul Brabban · Permalink · 17 Comments
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