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what is (x+(3+2i)) times (x-(3+2i)) ?

 Apr 7, 2016
 #1
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what is (x+(3+2i)) times (x-(3+2i)) ?

note that

 

\((a+b)(a-b)=a^2 - b^2\) 

 

and we get

 

\( (x+(3+2i)) (x-(3+2i))= x^2 -(3+2i)^2\)

 

\((3+2i)^2 = (9-4)+12i=5+12i\)

 

\( (x+(3+2i)) (x-(3+2i)) = x^2-5 -12i\)

 Apr 7, 2016
 #2
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Solve for x:
(-(12 i)-5)+x^2 = 0

(-(12 i)-5)+x^2 = x^2+(-5-12 i):
x^2+(-5-12 i) = 0

The left hand side factors into a product with two terms:
(x+(-3-2 i)) ((3+2 i)+x) = 0

Split into two equations:
x+(-3-2 i) = 0 or (3+2 i)+x = 0

Add 3+2 i to both sides:
x = 3+2 i or (3+2 i)+x = 0

Subtract 3+2 i from both sides:
Answer: |  x = 3+2i               or             x = -3-2i

 Apr 7, 2016

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