HELP!!!

Simplify the expression.
(-5i)(-3i)

a.15i
b.-15i
c.-15
d.15

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asked by Angela
  1. Of course you have to know that i^2 = -1

    so (-5i)(-3i)
    = 15i^2
    = 15(-1)
    = -15

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    posted by Reiny

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