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Compute (1+i)(1+2i)(1+3i).

 Jun 22, 2019
 #1
avatar+4624 
0

Expanding, gives us (1+i)(1+2i)=1+3i. Then, expanding again gives us (1+3i)(1+3i)=10.

 Jun 22, 2019
 #2
avatar+9675 
0

(1 + i)(1 + 2i)(1 + 3i)

= (1 + 2i - i) (1 + 2i + i) (1 + 2i)

= ((1 + 2i)^2 + 1)(1 + 2i)

= (-3 + 4i + 1)(1 + 2i)

= (-2 + 4i)(1 + 2i)

= -2(1 - 2i)(1 + 2i)

= -2 (5)

= -10

 Jun 22, 2019

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