# complex numbers inequality

• May 25th 2008, 06:39 PM
Solan
complex numbers inequality
i get everything until the red line, why is the next step like that? and where did the part on top of the green line come from?

http://img174.imageshack.us/img174/3199/mhcr2.jpg
• May 25th 2008, 06:54 PM
o_O
$|x|^{2} - 2|x||y| + |y|^{2} \geq 0$
$\Rightarrow |x|^{2} + |y|^{2} \geq 2|x| |y|$ ..........................................(Moved 2|x||y| to right side)
$\Rightarrow |x|^{2} + |y|^{2} {\color{red} + |x|^{2} + |y|^{2}} \geq 2|x| |y| {\color{red} + |x|^{2} + |y|^{2}}$..........(Added $|x|^2 + |y|^2$ to both sides)
$\Rightarrow 2|x|^{2} + 2|y|^{2} \geq |x|^{2} + 2|x||y| + |y|^{2}$......................(Simplified)