My course states that a polynomial is a Butterworth polynomial when it satisfies the following condition:
$|B(j\Omega)|=\sqrt {1+{\Omega}^{2\,n}}=\sqrt {1+{(\omega/\omega_p)}^{2\,n}}$
I'm really into accepting this, without having a lead why they use the modulus, to specify the requirements in the first place. Can someone help me with this?