Question

What is the right answer for 9i x 2i?

Answer 1

The correct answer is:   -18 .
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 9i * 2i = 18 i² .
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  " i " is an imaginary number equal to "√(-1) " .
  
  " i² " = [√(-1)] ² = √(-1) * √(-1) = -1 .
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   18 * i²  = 18 * -1  =  -18 .
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