Sunday, October 27, 2013

Verify the equality (1+i*square root 3)^2 + (1-i*square root3)^2=-4

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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