# [SOLVED] Problem with this question?

• June 21st 2009, 05:02 AM
mark1950
[SOLVED] Problem with this question?
Find the modulus and argument of $z1 \times z2$ where z1 is 3 - 2i and z2 is -2 + i.
• June 21st 2009, 05:25 AM
e^(i*pi)
Quote:

Originally Posted by mark1950
Find the modulus and argument of $z1 \times z2$ where z1 is 3 - 2i and z2 is -2 + i.

$z_1z_2 = (3-2i)(-2+i)$

Expand and simplify into the form $a+bi$ then use Pythagoras to find the modulus and $tan(x) = \frac{Im}{Re}$