Friday, October 31, 2014

What is the absolute value of z if 2z - z' = 3 + 2i ?

Given the expression:


2z ; z'
= 3+ 2i


We need to find the absolute value of
z.


First we will need to rewrite z using the form z =a+
bi


Then z' = a- bi.


Let us
substitute.


==> 2(a+bi) - (a-bi) = 3+
2i


==> 2a + 2bi - a + bi = 3+
2i


==> a + 3bi = 3+
2i


==> a = 3


==>
b= 2/3


==> z = 3 + 2/3
*i


Now we will calculate the absolute
value.


We know that:


l zl =
sqrt(a^2 + b^2)


==> l z l = sqrt(3^2 + (2/3)^2 =
sqrt( 9 + 4/9) = sqrt(85/9)


==> Then
the absolute value for z is l z l = sqrt(85/9) = sqrt(85) /
3

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