SOLUTION: i know (-6i) (-6i) is -36 but i don't know why. i can't seem to find out what i means.. negateve times negative , i thought was positive

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Question 144492: i know (-6i) (-6i) is -36 but i don't know why. i can't seem to find out what i means.. negateve times negative , i thought was positive
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
%28-6i%29%2A%28-6i%29 Start with the given expression

%28-6%2A-6%29%2A%28i%2Ai%29 Group like terms


36%2A%28i%2Ai%29 Multiply -6 and -6 to get 36


36%2A%28i%5E2%29 Multiply i and i to get i%5E2


36%2A%28-1%29 Replace i%5E2 with -1. Remember, i%5E2=-1


-36 Multiply


So %28-6i%29%2A%28-6i%29=-36