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$$
???
How do I reach that conclusion from:
$\displaystyle (x_1 + x_2)^2 = x_1^2 + x_2^2 + 2x_1x_2$
???
Cheers in advance!
Sorry to have to ask this, but I am stuck...
Why is this true:
$\displaystyle 2\left| x_1 x_2 \right| \leq x_1^2 + x_2^2$$
???
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!