Giải câu 4 bài: Số phức

a) $\left | z \right |=\left | z=-2+i\sqrt{3} \right |$

= $\sqrt{(-2)^{2}+(\sqrt{3})^{2}}=\sqrt{7}$

Vậy $\left | z=-2+i\sqrt{3} \right |=\sqrt{7}$

b) $\left | z \right |=\left | \sqrt{2}-3i \right |$

= $\left | z \right |=\left | \sqrt{2}-3i \right |$

= $\sqrt{(\sqrt{2})^{2}+(-3)^{2}}=\sqrt{11}$

Vậy $\left | \sqrt{2}-3i \right |=\sqrt{11}$

c) $\left | z \right |=\left | -5+0i \right |$

= $\sqrt{(-5)^{2}}=5$

Vậy $\left | -5+0i \right |=5$

d) $\left | z \right |=\left | -i\sqrt{3} \right |$

= $\sqrt{(\sqrt{3})^{2}}=\sqrt{3}$

Vậy $\left | -i\sqrt{3} \right |=\sqrt{3}$