SOLUTION: Write the expression as a complex number in standard form. -(3+i)(7-3i)

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Question 171398: Write the expression as a complex number in standard form.
-(3+i)(7-3i)
Found 2 solutions by jim_thompson5910, Mathtut:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
-%283%2Bi%29%2A%287-3i%29 Start with the given expression.


-%28%283%29%287%29%2B%283%29%28-3i%29%2B%28i%29%287%29%2B%28i%29%28-3i%29%29 FOIL.


-%2821-9i%2B7i-3i%5E2%29 Multiply.


-%2821-9i%2B7i-3%28-1%29%29 Replace i%5E2 with -1. Note: i%5E2=-1.


-%2821-9i%2B7i%2B3%29 Multiply.


-%2824-2i%29 Combine like terms.


-24%2B2i Distribute the negative.


So -%283%2Bi%29%2A%287-3i%29=-24%2B2i.


So the expression is now in standard form a%2Bbi where a=-24 and b=2

Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
-%283%2Bi%29%287-3i%29given
:
-%2821-9i%2B7i-3i%5E2%29multiplying factors
:
-%2824-2i%29combining like terms i%5E2=-1
:
highlight%28-24%2B2i%29multiplication by a negative 1