The radius of the circle represented by $(1+i)(1+3i)(1+7i) = x+iy$ is $(i = \sqrt{-1})$.

If $m_1, m_2, m_3$ and $m_4$ respectively denote the moduli of the complex numbers $1+4 i, 3+i, 1-i$ and $2-3 i$,then the correct one,among the following is

Let $z$ be a complex number such that $|z|-z=2+i$,where $i=\sqrt{-1}$. Then,$|z|=$

The complex number $z$ satisfies the condition $\left| z - \frac{25}{z} \right| = 24$. The maximum distance from the origin of coordinates to the point $z$ is:

The conjugate of the complex number $\frac{2 + 5i}{4 - 3i}$ is

If $Z = \alpha + i \beta$ satisfies the equation $|Z| - Z = 1 + 2i$ and $|Z| = \sqrt{\alpha^2 + \beta^2}$,then $Z \bar{Z} = $