Question 319283:   Let z = a + bi represent a general complex number. As noted in the lesson, the conjugate of z, abbreviated conj(z) or conj(a + bi) is the complex number a-bi. Also, the modulus of z, modulus(z) is the "size" of z, or SQRT(a2 + b2). Which of the following is true for all complex numbers?
 
I am having a really hard time with this problem. Help would be greatly appreciated. 
Thanks  
 Answer by stanbon(75887)      (Show Source): 
You can  put this solution on YOUR website! Let z = a + bi represent a general complex number.  
As noted in the lesson, the conjugate of z, abbreviated conj(z) or conj(a + bi) is the complex number a-bi.  
Also, the modulus of z, modulus(z) is the "size" of z, or SQRT(a2 + b2). Which of the following is true for all complex numbers?  
-----------------------
 
A All of the following 
False because E is not true 
--------------------------------- 
B z*conj(z) = [modulus(z)]^2 
--- 
true because (a+bi)(a-bi) = a^2+b^2 which is the square of the modulus 
------------------------ 
C z + conj(z) = 2a 
--- 
true because a+bi + a-bi = 2a 
-------------------------------- 
D z - conj(z) = 2bi 
true because a+bi -(a-bi) = a+bi-a+bi = 2bi 
-------------------------------- 
E None of the above 
False because b, c, and d are all true 
======================= 
Cheers, 
Stan H. 
  | 
 
  
 
 |   
 
 |