# Appendix A - Review of Complex Numbers - Exercises for A - Problems - Page 795: 5

$\overline{z}=1-2i$ and $|z|=\sqrt{5}$.

#### Work Step by Step

Of a complex number $z=a+bi$, $\overline{z}=a-bi$ and $|z|=\sqrt{a^2+b^2}$ Hence here, $\overline{z}=1-2i$ and $|z|=\sqrt{1^2+2^2}=\sqrt{5}$.

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