SOLUTION: simplify (6+3i)(2i-4)-(4i+5i)

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Question 999194: simplify (6+3i)(2i-4)-(4i+5i)
Answer by ikleyn(52800) About Me  (Show Source):
You can put this solution on YOUR website!
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simplify (6+3i)(2i-4)-(4i+5i)
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(6 + 3i)*(2i - 4) - (4i + 5i) = 6*(2i) - 24 + (3i)*(2i) -4*(3i) - (9i) = 12i - 24 + 6i^2 - 12i - 9i = -24 - 6 - 9i = -30 - 9i.

You make all calculations as if  i  is a regular symbol.
Remember that i%5E2 = -1,  and every time you have  i%5E2, replace it by  (-1).