SOLUTION: how do you simplify this expression?? (7+9i)(2-5i) help! full steps please

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Question 243656: how do you simplify this expression??
(7+9i)(2-5i) help! full steps please
Found 2 solutions by jim_thompson5910, Edwin McCravy:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
%287%2B9i%29%2A%282-5i%29 Start with the given expression.


%287%29%282%29%2B%287%29%28-5i%29%2B%289i%29%282%29%2B%289i%29%28-5i%29 FOIL.


14-35i%2B18i-45i%5E2 Multiply.


14-35i%2B18i-45%28-1%29 Replace i%5E2 with -1. Note: i%5E2=-1.


14-35i%2B18i%2B45 Multiply.


59-17i Combine like terms.


So %287%2B9i%29%2A%282-5i%29=59-17i.


So the expression is now in standard form a%2Bbi where a=59 and b=-17

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!


%287%2B9i%29%282-5i%29

Use FOIL

14-35i%2B18i-45i%5E2

Combine middle two terms:

14-17i-45i%5E2

Use the fact that i%5E2=-1

14-17i-45%28-1%29

14-17i%2B45

59-17i

Edwin