In conjugate gradient method, A is positive definite.
$\displaystyle x^{(k+1)}=\sum_{j=0}^{k}{\omega^{(j)}d^{(j)}} \ \ \omega^{(j)}>0 $
show that the sequence $\displaystyle \{ ||x^{(j)}|| : j=0,...,k+1 \} $
is monotonically increasing.