Saturday, October 16, 2010

What is (1 – 2i) ^6?

Given the complex number (
1-2i)^6


We need to
simplify.


==> We will rewrite the
power.


==> ( 1-
2i)^(2*3)


But we know that (x)^ab=
(x^a)^b


==> (1-2i)^(2*3) =
(1-2i)^2]^3


Now we will open the
brackets.


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


But i^2 =-1


==>
( 1- 4i -4)^3


==> ( -3 -4i)^3 = (-3-4i)^2 *
(-3-4i)


                         = ( 9 +24i + 16i^2) *
(-3-4i)


                       = ( 9+24i -16) *
(-3-4i)


                       = (
-7+24i)*(-3-4i)


                       = ( 21 -72i +28i -
96i^2)


                       = ( 21+96 -
44i)


                      = ( 117
-44i)


==> ( 1-2i)^6 = 117 -
44*i

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