Sorry to have to ask this, but I am stuck...

Why is this true:

$\displaystyle 2\left| x_1 x_2 \right| \leq x_1^2 + x_2^2$$

???

How do I reach that conclusion from:

$\displaystyle (x_1 + x_2)^2 = x_1^2 + x_2^2 + 2x_1x_2$

???

Cheers in advance!

Printable View

- May 20th 2012, 09:56 PMhowdigethereWhy is the following true ?!!
Sorry to have to ask this, but I am stuck...

Why is this true:

$\displaystyle 2\left| x_1 x_2 \right| \leq x_1^2 + x_2^2$$

???

How do I reach that conclusion from:

$\displaystyle (x_1 + x_2)^2 = x_1^2 + x_2^2 + 2x_1x_2$

???

Cheers in advance! - May 21st 2012, 01:12 AMemakarovRe: Why is the following true ?!!
- May 21st 2012, 01:34 AMhowdigethereRe: Why is the following true ?!!
dang.

Thank You emakarov!