First, we'll have to expand the binomials and we'll use
the identities:
(a+b)^2 = a^2 + 2ab +
b^2
(a-b)^2 = a^2 - 2ab +
b^2
According to these, we'll
get:
(1+i*sqrt3)^2 = 1 + 2i*sqrt3 - 3 (we've replaced i^2
by -1)
(1+i*sqrt3)^2 = -2 + 2i*sqrt3
(1)
(1-i*sqrt3)^2 = 1 - 2i*sqrt3 -
3
(1-i*sqrt3)^2 = -2 - 2i*sqrt3
(2)
We'll add (1) and (2) and we'll
get:
(1+i*sqrt3)^2+(1-i*sqrt3)^2 = -2 + 2i*sqrt3 -2 -
2i*sqrt3
We'll eliminate like
terms:
(1+i*sqrt3)^2+(1-i*sqrt3)^2 =
-4
We notice that the equality
(1+i*sqrt3)^2+(1-i*sqrt3)^2 = -4 is verified.
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