# complex numbers questions help

• Jul 23rd 2008, 03:32 PM
princessamme@hotmail.com
complex numbers questions help
I have coursework to do and I really want a good mark. This question that i am doing is not giving me nice numbers at the end, so if anyone can tell me what they get to make sure I'm not doing it wrong.

Q1 Let z = 3+5i and w = 3e^[(3*pi)/4] (w= 3 times e to the power of everything in square brackets)

Find:
1)z*w
2)z/w
3)z+w

thanks so much for any help :)
• Jul 23rd 2008, 03:44 PM
Mathstud28
Quote:

Originally Posted by princessamme@hotmail.com
I have coursework to do and I really want a good mark. This question that i am doing is not giving me nice numbers at the end, so if anyone can tell me what they get to make sure I'm not doing it wrong.

Q1 Let z = 3+5i and w = 3e^[(3*pi)/4] (w= 3 times e to the power of everything in square brackets)

Find:
1)z*w
2)z/w
3)z+w

thanks so much for any help :)

Let me guess

w=3e^[(3i pi)/4]

Just use the fact that

e^{ix}=cos(x)+i*sin(x)

EDIT:

http://www.gnux.be/latex/data/6a519a...c84afef796.png
• Jul 24th 2008, 02:04 AM
princessamme@hotmail.com
wups ye you were right i did mean 3*pi*i. i did that and got
w= [(-3*root2)/2] + [i*(3*root2)/2]. is this right? it makes the final answers quite complicated numbers, especially part 3 (z+w)
• Jul 25th 2008, 01:40 AM
berlioz